Best Defense against D4?

I have to say that the Slav is probably the best Defence to d pawn openings.

However you don't have to mind being the boring kid sat at the back of the class with no friends.

If you are a lovely person who has lots of friends you play Benoni systems the Benko Gambit etc,

Much depends on what you are looking for in an opening. Do you mean which defense is best against 1 d4 for winning purposes or for not losing purposes ?  The answer isnt the same to both questions. 

For someone with a limited knowledge of theory, I wouldn't recommend the King's Indian or Benoni.  These are fairly sophisticated lines, and you should have a solid foundation of basic theory under your belt before attempting them.  The first defense to d4 that worked for me was QGD-Lasker's Defense.  It is fairly straightforward and doesn't attempt too much; a good line to build your confidence with.  Tchigorin's isn't bad either; but learn one line in some kind of depth first, then take a look at something more radical.  Chess is like music, in this sense: Learn the scales first, then work on getting faster.  And like music, it takes practise, practise, practise.

Well, for me, most hypermodern openings, where you don't challenge white in center right away, somehow turn out to be passive.

Did you play through that game I posted on the previous page? Hardly passive!

I've fallen in love with the Albi Countergambit, the Grundfeld Defense and I'm willing to learn the Benko or the Benoni.

I was trying the Englund Gambit, and was told by GM Fleer, to play the Budapest because it can be played at GM level. I agree with the others true enough, but really no good answer to the question really. What suits your playing style. The idea in the opening is to gain an imbalance and get a playable middle game.

I play the Tarrasch Defense, is it the best response? I don't know...

Indeed one of the most aggressive defence u can choose. white gains more space with pawncenter yes, but passive? no!

trouble with the KID is wimps can play the Exchange Variation and go for a boring draw, you can play the Nd7 but I think this is an inferior line and kind of rewards boring white players

The exchange KID has a high % of draws but black wins more often than white so its fine for black. 

Exchange French drawish... That sounds so easy. Draw in open game without e pawns... Easier said than done.

@Sceadungen

The Slav Proper isn't boring at all in many lines. Black can castle queenside if he wants. And then theres the Bishop Sac for 3 pawns line too.

And for playing the KID, I'd honestly be more worried about the Bayonet Attack. If Black doesn't know what he's doing, white can get quite a bit of pressure  after stuff like c5,cxd6,Nc3-b5,Nf2-d2-c4. And in the main Nh5 line, white seems to be doing well too.

And for the Exchange KID variation, wouldn't you say that if your (possibly lower rated) opponent is going for a draw, you have a better chance to win?

 My experience with Slav players has been very negative, mostly they are game killers looking for a draw, been unlucky I guess.

The bayonet attack is not too scary, but there are many lines, other than ...Nc3 that allow you to avoid it ...Na6 is interesting and fun.

Agree on lower rated players looking for a draw, yes you can win the ending as Fischer showed, but it is a long and tedious job, that I prefer to avoid by move ordering them out of the exchange variation.

the idea behind the King's indian is generally black gets a space advantage (after e5 and f5) on the kingside and white gets a space advantage (after d4, c4, and often b4) on the queenside. and where you have a space advantage you generally are the attacker. so, black is usually attacking white's king in this opening.

I agree w/ the others though, when studying openings, try to play to your strengths. If you like tactics, play semi-slav, benoni, dutch. for positional play, try queens gambit declined, benko gambit ( yes, this is a POSITIONAL gambit!) Nimzo-indian, or queens-indian.

at your strength, steer clear of the KID. It is too theoretical. a knowleadgeable opponent will know all the tricks.

Most of all, study some games. If you like the resulting middle game pawn structures that arise from a certain opening... study that pawn structure! that will improve your game more than just looking at a few lines.

I too struggled with this for a while, and tried most every possible defense. I have settled on the Dutch. It opperates under somewhat similar concepts as the Sicillian, in that you unbalance the position. Of course, in the Dutch, you are weakening the kingside a bit, so it is a bit dicer.

There are three main lines... the Stonewall is the most solid, and easiest. The Leningrad is the sharpest. I like the Classical myself, with a queenside fianchetto.

I thought the classical with the Q-side fianchetto is  only good for when white skips out on g3 and plays Nc3 and you answer with Bb4+b6, going for a kind of Nimzo-type defense but without having to move the knight?

I dunno, I certainly don't claim to be an expert, I do it in almost all cases. Even if they fianchetto on the opposing side, I'm happy to trade their kingside bishop for my queenside one and leave a hole in thier defenses.