1. d4 best 1... Nf6 line. your opinion

i see and play 1. d4 a lot therefore i know a fair bit about the 1...Nf6 lines. and there are a few 1... Nf6 lines. i play the Kings Indian defence however i want to experiment with some of the other lines.

so should i stick with the Kings Indian or should i change to something else.

Do  you play OTB tournaments?

yes but only recently

1,d4 c6 Caro-Kann is an excellent drawing weapon when you need it in a tournament.  yes, it can transpose into other openings.  But, you will find most opponents respond with 2.e4

yes, the Caro-Kann can transpose into the French Defense.  But, only if Black allows it.

i know the Caro-Kann. i was more looking for 1...Nf6 lines.

There are many KID defenses.  It all depends on what plan of attack White chooses, what variation of the KID Black has to transpose into.  If  you are looking  for  strong player insights I will  post some for you, but  not right now. I am tired and am going to get some sleep.  I will give you one hint about the Saemisch and what Smyslov discovered.

the KID isn't the only option for black if he does 1...Nf6. you've got the Nimzo Indian, the Queens Indian defence, the Benoni, the grunfeild and more.

You haven't been playing the KID long enough to branch out into transpositions.  Especially not the Benoni where there is great difficulty for players to calculate when to execute pawn breaks.  There is great risk in being either too early or too late in the execution of a pawn break.

I will give you insight shortcuts in the KID.  When you are rated higher I will be glad to give you insights into the transpositions.

I will be glad to help you.  Please don't bite off more than you can chew.  That I won't help you with.

i've been playing the KID for quite some time now and have had a lot of games with it. not many on this site but at my chess club it's what i always play now. 

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Do you know what Vassily Smyslov discovered about the Saemisch?  If you do then please post it.  If you don't , I am having trouble getting to sleep.  But I promise  you I will share that insight shortcut and many others.  In the meantime see if you can find what Smyslov discovered by googling it. 

As for Black against 1.d4 (I myself very seldom play 1.d4 as White) - I like 1. ... Nf6 (from time to time playing 1. ... d5 intending 2.(c4) c6) - and as for 1.d4 Nf6 2.c4 - I am fond of the Nimzo-Indian defense (of course it also may arise the Catalan or Queen's Indian, depending on White's third move)

https://www.chess.com/blog/schachfan1/exciting-nimzo-indian

I have been pretty busy.  Sorry  it took me so long to get back.

First I want to  share  a short story with you.  Back in 1975 I lived in Orlando, Fl.  I was lucky enough to have  as a houseguest and friend  GM Ron Henley.  One  morning while  he was living with me some Jehova's  witness ladies came to the front door.  I let them in and we sat in the living room.  Ron was seated with  his back to us at the dining room table working  on  his daily  chess.  The  ladies and I talked for about 10 minutes.  They  saw  that they weren't making any progress with me, so the younger  lady raised  her voice  a little and said to Ron, "...What about you sir, what do you believe in..."  Ron never turned around, he  just responded in a very matter fact tone  of  voice, "...I  believe  in the King's Indian  Defense..."  Since Ron had his back  to them, the  two  lladdies turned to me with a quizzical look on their faces.  I didn't say anything to them.  They just quickly said their goodbies and  I escorted them to the door.  After the ladies were gone Ron and I laughed our asses off.

Ok, now to chess.  If you know about the Maroczy Bind then you probably know about the Boleslavsky Wall.   If you have been playing the KID then you know  that  a characteristic pawn  structure  that  results is  the  Maroczy Bind.  But sometimes the Boleslavsky Wall results.  Most average chess players  considered  both to be just the Maroczy Bind like pawn structure.   The truth is  that of the two pawn structures Black would much prefer to have the Boleslavsky Wall.

The Wall  wire frame pawn structure is White pawns at c4 and e4 and Black pawns at c6, d6 and f7 with a half open e-file on  Black's side.  The  wire frame for the Maroczy Bind is White pawns at c4 and e4, with Black pawns at , d6, e6, and f7.  There is a  half open c-file on Black's side.  The half open e file of the Boleslavsky Wall makes all the difference in the successful defense of the Black position.

Next time we will get into diagrams and  moves  based on those two pawn structures.  

For me it looks like the Nimzo indian is the best, but you have to play some other stuff after 1. d4 Nf6 2. c4 e3 3. Nf3, e. g. the queen's indian or the queen's gambit declined. And there is the catalan. Black is fine everywhere, but i think it's not the best way to open the game when you have to win.

Grünfeld, King's indian, Benoni and Wolga Gambit are also fine, well respected and well scoring openings with more wins for both players.

For my personal taste minor openings like the budapest gambit or the old indian defence are great practical weapons. The 1. d4 mainline player has to take care about all of theses major openings (QGD, QGA, Slav, Semi-Slav, the named openings above, the dutch), his preparation ends after something like 10. XY +/= "white is better". And then the better experienced black player strikes back over the board.

What's the problem you've been having in the King's Indian?

Perfectly fine opening, and what's cool about it is that it's so inherently flexible that within it black can choose a number of setups. For example black, after 1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Nf3 0-0 6. Be2 can play many different ways. He can play 6...c5 (which I kind of enjoy- very different type of position), or 6...e5, or 6...Na6/Nbd7 with e5 later. If he plays 6...e5 then after 7. 0-0 he can play Nc6, the super-theoretical mainline, Nbd7, Na6, or exd4 (completely different sort of position), and they're all different (although Nbd7 and Na6 are somewhat similar in themes). 

Similarly against the fianchetto there are only about five different setups, ditto for Saemisch. It's true that probably there aren't so many for the Four Pawns, but the Four Pawns is not considered a terribly serious try anyway.

Why leave the KID?

i'm fine with the KID but i want to experiment with some other 1...Nf6 openings