It's quite interesting to look at the top level cc - player's opening favorites.
Against 1.e4:
Almost everybody is playing Sicilian, Sveshnikov and Najdorf
No more Dragon oder other Sicilian lines seems to be playable at top level.
1.... e6 (French) and 1....c6 Caro Kann are rarely played.
A little bit more frequently is 1....e5. But I think that also the old Ruy Lopez is not really popular among the cc cracks.
Against 1.d4:
Here seems to be more diversity:
But I think The Slav is definitely the most popular Black's defense, followed by Nimzo Indian, Kings Indian and Queens Gambit.
Benoni and Wolga Gambit seems to be dead here.
What do you think, is there no more space for French, Caro Kann and Aljechin Defense in todays cc practice ?
Is Dutch and Modern Benoni no longer playable ?
In the sixties Hans Berliner won the ICCF championship with Aljechin Defense