Question Best AM4 cpu for medium 1080p gaming?

^ I agree.
Ryzen 5 2600 on a decent B450 (or even B350/X370) MB would work very well with your GPU for low/medium settings at 1080p/60Hz.
I had a Ryzen 5 2600 running at 4 GHz with my GTX 1660 Ti (1080p/60Hz) and it had no problem running AAA games set to Ultra or Very High anywhere from 85 to 120+ FPS depending on the game.
My CPU never exceeded 55 to 60% usage, with my GPU at 90 to 99% usage.