What a great question! I've played both the classical and the Winawer and have finally come down definitely on the side of the Winawer. My next day off is Wednesday ( though I may have time Tuesday ) and I'll be glad to share my thoughts and experiences. Until then...odyson.
Winawer vs Classical

This is an interesting topic to me for several reasons. My wife and I both play the french defense as black. I prefer the winawer and she prefers the classical. I sometimes do play the classical too, though its rare . I think this is just a matter of personal preference and which positions you like/understand better. I think the winawer is more complex/critical..... giving both more winning and losing chances. You will win, and lose , more with the winawer I believe than with the classical but the % of draws is higher in the classical. So... my choice also depends on what I want from the game, if I MUST win then I will choose the winawer over the classical but if a draw is also ok then I would go with the classical. I think a true french enthusiast simply should play/learn both and decide later which they prefer.

I tried Winawer for some time but every time I met an opponent with firm knowledge of White play I could not reach an equal position. Therefore I think Winawer is not sound. I don´t think any of the top guns play Winawer.
Therefore I switched back to Nf6 with much better results ...

I tried Winawer for some time but every time I met an opponent with firm knowledge of White play I could not reach an equal position. Therefore I think Winawer is not sound. I don´t think any of the top guns play Winawer.
Therefore I switched back to Nf6 with much better results ...
How many top guns play the classical french ?

Morosewich and Kortschnoi for sure. And I remember also one or two games from Iwantschuk and Topalow.

Thank you for your insights guys.
Here's a position of a main-line Winawer game development, with best play on both side. I can't help but share Winnie Pooh's opinion when I see this. Equality is not reached when White knows the main line well, at least not at this point in the game, and probably not later if White keeps playing well.

However, after a good play by White and Black in the Classical variation, we reach through the Burn something like this, which seems to me more equal.

(I forgot to invert the last diagram.)
For the moment what I know from the Winawer variation is very limited though, and comes mainly from the John Watson's book "play the french" 3rd ed, and some games I played, so I may not be aware of other possible Winawer lines. I took a look at the Winawer line with the Bishop going back one square instead of taking the Knight, but the continuation doesn't seem much interseting for Black.
I ordered yesterday a book on the Classical variation, "french classical" by Byron Jacobs. I cannot wait to study it.

Morosewich and Kortschnoi for sure. And I remember also one or two games from Iwantschuk and Topalow.
Korchnoi did play the classical more than the winawer but he was far more successful when he played the winawer: winning 57% with the winawer and only 25% with the classical. He played the classical in about 22 games more than he did the winawer. His % with the winawer = 57% win , 24% draw and 19% lost
His % with the classical = 25% win , 55% draw and 20% loss.
These figures support what I was saying nicely btw.

I'm still practicing the Winawer by the way, it seems that the more the middle game evolves, the better Black's position gets. However the King side stays under constant pressure, and development is quite slow.

Here are some exerts of an interesting article I found there: http://www.ez-net.com/~mephisto/Understading%20the%20French.html
The Winawer
The Winawer after 1.e4 e6 2.d4 d5 3.Nc3 Bb4 leads to some of the most interesting and volatile systems of all of chess opening theory, and its popularity seems to continue unabated into the next millennium Extremely tactical and sharp systems exist next to heavy-blooded strategical positions that exact a high degree of skill from both players to play successfully. The main line Poisoned Pawn Variation alone provides enough reason to take up playing the French Defense, although it has to be said in all honesty that the extreme sharpness of this system has at times actually contributed to an increase in other French Defense systems, such as the Classical Variation. The reason for this is, as is true for any other exceedingly sharp opening systems is that many say they are unplayable. It is however also true that thus far Black player have always been able to put the ball back in White's court with the introduction of suitable improvements.
When playing the Winawer it is therefore important to remember that a large amount of theoretical knowledge is absolutely essential for surviving the many dangers inherent in its complexities. Black and White player alike need to arrive at every contest heavily armed with the latest innovations and improvements.
The recorded history of the Winawer Variation begins in 1861 when the variation was employed twice in the London match between Louis Paulsen and Kolisch, viz. Paulsen,L - Kolisch,l ½ - ½ The variation's namesake, Simon Winawer (1838-1920), a strong Polish master born in Warsaw, does not appear until he played 3…Bb4 against Wilhelm Steinitz at eh Paris Exhibition of 1867, viz Steinitz,W Winawer,S 1-0 Paris 1867. Mikhail Botvinnik wrote in 1975 "to be quit3e frank, the real history of the French Defense starts with Aaron Nimzovich. "Nimzovich's original analyses and practical experiments with both the Winawer and the Advance Variations in 1920s brought the French Defense into maturity as a formidable weapon for the second player. His research set the stage for further discoveries by Alexander Alekhine, Mikhail Botvinnik and other Soviet player in the 1940s.
The Winawer Variation, or Nimzovich Variation as it is known in Europe, is a controversial opening. The highly complex, sharp and unbalanced positions that result appeal to many styles of play, offer Black real winning chances, and provide one of the main reasons for playing the French Defense! Throughout history the Winawer Variation has been associated with uncompromising player like Robert Fischer, Vasily Smyslov, Mikhail Tal, Boris Spassky, Ljubomir Ljubojevic and Jonn Nunn, who have scored many stunning victories from the White side; while Wolfgang Uhlmann, Aron Nimzovich, Mikhail Botvinnik, Viktor Korchnoi, Lajos Portisch and Rafael Vaganian have played the Black side with great success. There is even a short but distinguished list of exceptionally fearless competitors who are willing to play the Winawer from either side, including David Bronstein, Nigel Short, Boris Ivkov, Alexander Alekhine, Jan Timman and Sergey Doimatov.
Perhaps the words of former World Champion Robert Fischer, written in 1969, sum up the controversy best: "I may yet be forced to admit that the Winawer is sound, But I doubt it! The defense is anti-positional and weakens the kingside." In spite of his advantage in terrain, White often finds it difficult to locate a point at which he can attack in the complicated positions that are typical for many of the Winawer lines. White theoretically has the superior position, but in practice his advantage often evaporates. If he does not succeed in quickly developing an initiative, then the weaknesses in his position sooner or late become decisive targets for his opponent.
With 3…Bb4 black transfers his dark squared bishop from his kingside with the idea of exchanging it on c3, disrupting White's queenside by doubling his c-pawns, but concedes the bishop pair. This results in an unbalanced position characterized by long term strategic tension and immediate tactical complexity. White seeks to capitalize on the absence of Black's dark squared bishop by attacking the kingside, immediately with Qg4 or later following a deployment of forces. Black's kingside, especially the dark squares, suffer a troublesome long term weakness, his light squared bishop finds itself blocked by pawns, and yet Black' position has a definite resiliency both in attack and defense. Black generally operates on the queenside, but he may also have the possibility of blockading the queenside and counter attacking in the center. White is plagued by a certain urgency to commence offensive operations because of his vulnerable queenside and the disunity between the two fronts, which typically results from his doubled and immobilizeds c-pawns.
After White's main reply 3…Bb4 4.e5 the position takes on a semi-closed character, which does not appeal to all White players. Several 4th move alternatives exist, namely 4.a3, 4.Qg4, 4.Bd2, 4.Bd3, 4.exd5 and 4.Qd3. Although none of them threaten the soundness of the Winawer, each enjoys periodic popularity and requires accurate treatment by both players. The fundamental starting position of the Winawer arises after the natural 1.e4 e6 2.d4 d5 3.Nc3 Bd4 4.e5 c5 5.a3 Bxc3+ 6.bxc3 Ne7. White has acquired the bishop pair, secured a space advantage and fortified point d4, in exchange for incurring significant structural weaknesses on the queenside and a division of his force. While other 5th moves such as 5.Nf3, 5Bd2, 5dxc5 and 5.Qg4 are terribly popular they are once again logical and dangerous enough to test both player. In the main variation White now has a choice between the ultra-sharp and critical 7.Qg4, and the positional continuations 7.Nf3, 7a4 and 7.h4. The latter treatments allow White to try to defend his center, as opposed to allowing …cxd4 and …dxc3 in the former. From a position of central strength, White then has a number of ways to attack on both sides of the board, viz. h4-h5-h6, Bd3 with Nf3-g5, a4 and Ba3, or even with dxc5 with Nd4. Black in turn puts pressure down the c-file, blockades the queenside by …Bd7-a4 or …Qa5-a4 - with or with out …c4 - or turn his attention ot the center by …f6 with a subsequent attack along the f-and f-files. The extreme flexibility of both side's strategies has made this fertile ground for endless new idea and refinements.
The Classical Variation
In the Classical Variation of the French Defense, Black's plan is to firmly defend the light squares in the center, and then try to undermine the e4-square with moves such as …c5. White now chooses between 4.Bg5 and 4.e5. For many years 4.Bg5 was considered more popular, but not anymore.
The Classical Variation is enjoying a renaissance these days and World Championship challenger Nigel Short is leading the charge. Now White can play 4.Bg5, which allows either a pure Classical with 4…Be7, or a MacCutcheon with 4…Bb4. Often White avoids both by putting the question to the knight immediately with 4.e5.
Classical Variation Overview
The classical Variation has been eclipsed in popularity by the Winawer Variation for some fifty years. However, it is currently experiencing a revival, and many of the nearly forgotten lines have come under considerable theoretical scrutiny, and received much needed revision and updating in recent years. Players like Victor Korchnoi, Nunn, Kortschnoj, Short and Jan Timman, for example have done much to energize certain lines with new ideas, and a number of systems in the Classical Variation can now be employed by ambitious second players looking for more than equality. It can also be said that much of the material has undergone quite a exploration offering an attractive practical opportunities for well prepared players.
While most of the systems are not as unbalanced as some of the extremely chaotic main Winawer lines involving Qg4xg7, they still offer a variety of interesting and rather difficult problems for both player. Black aims to combat White's central space advantage with more traditional means than he does in the critical Winawer main lines, but he does so without incurring the severe penalty of giving up his kingside. White generally enjoys a small edge due to his space advantage in the center and on the kingside, but Black is able to develop comfortably and can exert sufficient pressure on White's central position provided he plays energetically enough. Some lines, particularly in the Alekhine-Chatard Attack and the MacCutcheon Variation, require detailed and up-to-date knowledge of the latest theoretical discoveries to meet successfully in class tourneys.

Wow! You guys have done a great job in your comments. I don't have a lot to add. I played the poisoned pawn variation for years with great results. Eventually I came across some games that cast doubt on it's soundness. Check out Psakhis' book French Defence 3Nc3 Bb4 and look up the game Geist-Borchers with the footnote game Goloshchapov-Ahlers. These games caused me to have an existentional crisis about my all time favorite variation.
Now I understand that Moskalenko has done much to revive the line but I haven't checked it out yet. In the mean time I switched to the 6. ...Qa5 line which has made me quite happy.

I should mention that I've also played the classical but I often feel like I'm playing for a draw; unlike the uncompromising Winawer. Maybe that's just a personal bias. At any rate , the McCutcheon is pretty interesting and it's sharpness and relative rareness should reward it's advocates with a lot of victories.

I'm still practicing the Winawer by the way, it seems that the more the middle game evolves, the better Black's position gets. However the King side stays under constant pressure, and development is quite slow.
Yes - that is the main point !
You have to like messy positions and you should not mind playing with reduced king safety otherwise Winawer is the wrong defense for you. Probably that is the reason why I performed poorly with Winawer.

Morosewich and Kortschnoi for sure. And I remember also one or two games from Iwantschuk and Topalow.
Korchnoi did play the classical more than the winawer but he was far more successful when he played the winawer: winning 57% with the winawer and only 25% with the classical. He played the classical in about 22 games more than he did the winawer. His % with the winawer = 57% win , 24% draw and 19% lost
His % with the classical = 25% win , 55% draw and 20% loss.
These figures support what I was saying nicely btw.
Do you know the average rating of the competition in both cases? If he only played the Winawer against relatively weaker players, these numbers only prove that Korchnoi wins more against weaker players than against stronger GMs. My Chessbase is down while I revamp my hard drive, so I cannot check myself but will do so within the week.

This is an interesting topic to me for several reasons. My wife and I both play the french defense as black. I prefer the winawer and she prefers the classical. I sometimes do play the classical too, though its rare . I think this is just a matter of personal preference and which positions you like/understand better. I think the winawer is more complex/critical..... giving both more winning and losing chances. You will win, and lose , more with the winawer I believe than with the classical but the % of draws is higher in the classical. So... my choice also depends on what I want from the game, if I MUST win then I will choose the winawer over the classical but if a draw is also ok then I would go with the classical. I think a true french enthusiast simply should play/learn both and decide later which they prefer.
how does castling opposite have draws?
Hey mates. I've started to play the French defense about a month ago. Against Nc3, I started to learn and play the Winawer variation exclusively. The Winawer is very sharp and sometimes deadly for White when White deviates from the main line. However, I feel that Black's position isn't really effective when White plays the main line with 7.Qg4. White's center is solid, they have an open file for their rook on the Queen side, and control over the b1-h7 and c1-h6 diagonals. Black needs to face a progressive methodological attack on its King side, and lacks the black-square Bishop that is usually very important in the French defense as it is the only active Bishop during the opening and most part of the middle game. For this reason, I started to get interested in the Classical variation. I'm now just starting to study it, and I must say that against best play by White, I have the feeling that the Classical variation is more flexible, less commited to one particular position, and more solid in general. I am however very surprised to see, in the GM databases, that the Winawer is more popular than the Classical variation. Why? I haven't been able to find yet a flaw in the Clasical variation that could justify switching to the Winawer, except maybe the need for quick sharp play in Blitz. What do you guys think?