The gtx 960 is not even thing to mention here the r9 390 just obliderates it in every case
As the r9 390 rivalls with 2 gtx 960s in sli and is fit in your budget i wouldnt even be looking at the 960
Except 1 case if you are heavily into moba games (like myself) mostly playing league of legends if thats the case the 960s far less power consumption and faster react times make it a better choise