Best way to attack the Najdorf as White?

Recently, I have faced the Sicilian Najdorf in a lot of games—and I am still brought to a halt on making my decision of what to play against it. I have played the Amsterdam Variation with 6. f4 in my recent games as I prefer this sudden strike in the center rather than a slower theory-based game with Be3, which I see is played most at master level. I would consider myself an extremely aggressive player and find it quite easy to spot tactics, if there are any variations of the Najdorf that you know of, which feature less theory based lines and more intuitive attacking positions I would love to hear what you have. For a little more knowledge, my chess game repertoire is as follows

White:
With E4: Ponziani Opening 
1. e4 e5 2. Nf3 Nc6 3. c3

With D4: Nimzo-Indian: Classical Variation
1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2

Black:
Against E4: Caro-Kann Defense
1. e4 c6

Against D4:
Benko Gambit / Grunfeld Defense
1. d4 Nf6 2. c4 c5 3. d5 b5 / 1. d4 Nf6 2. c4 g6 3. Nc3 d5 

With White I almost never play D4.

Have you tried the old mainline Bg5?

Yes and I end up in this position with my invented move Bg2

It seems very dull and most games lead to a draw.

Make it easy and avoid it! Make 3.Bb5+ and learn that well. Too much theory in mainlines. If you still want a mainline chose 6.h3.

The most logical moves are probably 6 Bc4 and 6 Be2: develop the bishop and prepare O-O. Of course 6 Bg5, 6 Be3, 6 a3, 6 a4, 6 f4, 6 f3, 6 g3, 6 h3, 6 Rg1, 6 Qd3 are viable too.

What's wrong with 12. g5 and 13. f5?

there are a lot of different ways to play the Najdorf, pretty much all of them are decent for both sides. Personally I play the English attack as I dont like f4 because I feel overextended and I find the main line too complex. 

1.e4 c5 2.Nf3 d6 3.Bb5+ 

A great way to lose respect among your peers LOL 

Because of the line I gave. Qh5 followed by Nxe6.

If you are planning to "attack the Najdorf as White", then of course Black will get counter-chances. The Najdorf wouldn't be a sound opening, if he didn't.

Maybe you're not cut out to be an Open Sicilian player?

Closed sicilian

I guess you could play that weird h4 move or something like that, just try to launch an attack straight away? other than that if black plays into the Main line maybe the poisoned pawn variation or something

I only have come across the Najdorf a few times, but against the Sicilian I like to go for the English Attack setup with Be3 Qd2 and O-O-O with f3 g4 etc.

The good news: If you like sharp, attacking games, playing against the Najdorf affords you lots of opportunities.  It even gives you a wide range of ways to start them -- Bg5, Be3, h3, f3, Bc4, even Rg1.

The bad news: None of these are just a simple ambush.  The Najdorf affords black lots of defensive ideas and lots of counterattacking ideas.  If, say, the English Attack is "too slow" for you, then you may be out of luck.  Which is a shame, because black won't always play an oppening that appeals to your taste for a sharp, tactical fight, so if that's what you want, it would seem you'd enjoy learning some one or more of the ways to initiate it.

For my taste, the 6. Bg5 lines are the most fun.  They involve a lot of theory,  but if you're playing someone at your level, there's no reason to supose they know the theory better than you. And there are a lot of thematic ideas that recur across variations.

3. Bb5+ is not good for aggressive players as you get very dry positions where white doesn't have much to play for in terms of an attack. It is more for high-level, positional players.

6. Bg5 and 6.Bc4 are perfect variations for dynamic, aggressive players. You don't need to learn so much theory at lower levels as no-one else knows it either and it's just a game of chess.

6. h3 (with idea of g4) is also a cool variation. It's kind of a mix between positional and aggressive styles.