I would either get a HD 7870, HD 7850 or a 650 Ti boost depending on how much you wanna spend. With the 650Ti boost and the HD 7850 performing around the same, you can expect to play with high setting but without the little plus like Anti Aliasing turned to the max.
For ultimate performance and a price that fit your budget I would get a HD 7870. You'd be able to pretty max out BF3 and Bioshock Infinite but maybe uber max out FarCry 3, from what I've heard its a veryyy demanding game but you should be able to run it at more than decent settings!
I would pick this card from XFX:
the warranty of XFX is legendary, and despite what some said, the cooler is very decent! (Plus you get bioshock infinite and tomb raider for free!)
Hope it helps!