GTX 690 all day, its the better card and they're practically the same price.
But the guy's are right you'll save a couple hundred by buying the GTX 780 and that will play anything on the market.
The only way I'd entertain a GTX 690 is if A) you have money you just don't want, B) your running multi 1080p screens on Ultra settings and you won't compromise a single frame per second.