yea gtx 760 out performs the 270x by a little bit. both cards are good especially for there price. id say if you can squeeze another 40 dollars go for the 760.
also i dont think to many games support mantle right now. i know bf4 does but they built the game with amd r9 series in mind.
I've heard this question so much recently, and honestly I've seen the 270x has a VERY small performance difference that makes it SLIGHTLY better then the 760, and seeing as mantle and all that is coming out in the near future, I would go with the 270x. However, the 760 is more trustworthy and I've already seen some failed 270x's. But I think the 270x barely takes the win in this category, and it's a bit cheaper. Hope this helps!
you can buy that 760 superclocked and over clock it alittle more and it will perform close to the 770 but at the 249 price. thats pretty nice. and that card came down in price a little. a couple days ago it was 255.99
It's quite surprising actually the R9 is actually better than the 760 in BF4 in this benchmark, and 40 dollars cheaper!? Sounds like heaven.
http://www.techspot.com/review/734-battlefield-4-benchmarks/page2.html
It's because the card was optimized for the game and vice verse, BF4 was made for AMD cards, so they will always perform better in this game.