Its hd7970-> R9 280x vs gtx680->gtx770 and gtx770 and r9280x trade blows in some games but gtx770 gets some (<5) fps more in the majority of games...
If you play EA games a lot, mantle is coming to AMD cards, if you want high physx and shadowplay take nvidia. Most other 'exclusive nvidia features' (like 4 of 5) are also available for AMD...