Wanna know what part should I upgrade next?

A while ago I bought a new cpu for my desktop pc and I want some advice on what to upgrade next. I've been thinking of getting a new graphics card, but my current GTX-1080 has been mostly capable of handling all the games I like to play. There are still some games I'd like to try, but my computer just can't handle it. What should I do next?

I couldn't find my psu, case, or cooling fans on pcpartpicker, but I've got roughly what my psu is capable of.
https://pcpartpicker.com/list/T2NK2k

I live in the U.S., there are no MicroCenters nearby. I would likely be getting my parts from Best Buy. My current main monitor is 1920x1080 75Hz, but I plan to get a 100-150Hz monitor. This is all just for casual use, and ideally I would get something up to a couple generations newer than my current graphics card, I just wanna know what might pair best with what I've got.