http://ca.pcpartpicker.com/parts/video-card/#X=40111,869110&sort=a8&page=1
Either the Geforce 970 or AMD 390. Look up benchmarks for the games you want to play and see how the cards do for them. They are roughly the same and trade blows back and forth between the two, and fanboi's will tell you one RULEZ over the other and one suX bad cause his bro had one and got bad FPS once, so you know, he know GPU's better than all.
It comes down to those two cards in your price range though, so google and go from there.