a FX-8320 with OC @4.2-4.5GHz? and a good Cooler?
-> go for the RX 580 8G - is enough to play most games in VeryHigh-Details in 1080p with sufficent framerate
without OC and not willing to OC and buy a new Cooler? or on a Budget
-> go with a RX 570 4G
or you can play with the fire and get a 1060 6G (DONT consider the 3G version)
also it kind of depends on what of that Cards you can get the best price for
PC: R7 2700X @PBO + RX 580 4G (1500MHz/2000MHz CL16) + 32G DDR4-3200CL14 + 144hz 1ms FS P + 75hz 1ms FS
Laptop: R5 2500U @30W + RX 560X (1400MHz/1500MHz) + 16G DDR4-2400CL16 + 120Hz 3ms FS