Hello,
Here is a selections of GPUs that i thing are pretty good:
EVGA GeForce GTX 960 (http://www.amazon.com/Gigabyte-Gaming-Graphics-GV-N960G1-GAMING-4GD/dp/B00VBNT3X0)
Or
Gigabyte GTX 960 G1 Gaming (http://www.amazon.com/Gigabyte-Gaming-Graphics-GV-N960G1-GAMING-4GD/dp/B00VBNT3X0)
If you are wanting to go a little higher I would recommend the EVGA GeForce GTX 980 (http://www.amazon.com/EVGA-GeForce-Cooling-Graphics-04G-P4-2982-KR/dp/B00NI5DA2E)
Hope This Helps, Lewis W