Personally feel the one plus slim cases offer a lot of variety like bamboo, Kevlar etc and they look good and are slim as well.
Tudia makes great thin cases. Looks like there only pre-order right now though.
Here you go: https://www.amazon.com/OnePlus-TUDI...ag=hawk-future-20&ascsubtag=UUacUvbUpU5228626Where do you find those?