Depending on your budget I would say anything above the GTX 960 or R9 380 ($180-$230) would be perfect for your CPU. The lowest I recommend would be the GTX 950 or the r7 370 which go for $150.
Ultimatly if you are like me and dont mind old and used hardware as long as they perform good then something like a GTX 660 from Ebay would do the trick, those usually sell for around $80-$120. If you are lucky you could find it even cheaper. I just got lucky and bought a GTX 780 for $200 early this afternoon.
BTW what Power Supply do you have?