my fav is the nimzo
GM's Most played defense against d4
In the last few years the Slav has probably become the most played defence, especially the Chebanenko variation with 4.a6. I guess the Kings Indian may be the next most popular choice.
According to the databases,
1.d4 d5 2.c4 c6 occurs in just over 1 in 4 games. Yes, that can transpose to other QGD lines, but it starts out as a Slav
1.d4 d5 2.c4 e6 occurs about 1 in 20 games
1.d4 Nf6 c4 e6 occurs in more than 1/3 of all GM games, with Black opting for the Nimzo Indian or QID in the great majority of games. The QID is more popular than the Nimzo right now. That of course is because white tends to avoid it!
What's GM's most played defense against d4 actually?
(and what's your favorite)?