Update:
Just FYI, but once games start to code for DX12 and Vulkan better your FX-8320 is going to work a lot better for those games.
Avoid AMD GPU's because your weaker CPU is going to be even more of a bottleneck for DX11 titles since AMD's DX11 drivers use more of the CPU (so if it's already a bottleneck you'll be losing even more).
GTX1070 too expensive?
GTX1060 6GB is the only other solution I can recommend.