First of all I don't play as a titles. Omainly games like tf2 and cs go.
I went with a 970 over a 390 x cuz nvidia is slightly better for source games, esp tf2. I wanted a evga psu but evga Is hard to find in Asia where it's prices can be much more than corsair.
I went with a 850 watt psu cuz I don't plan to buy another one next time when I build an slightly build.