Cosmic is quite nice. There's some polishing left to do, but it's already pretty solid. The app store is a bit of a turd, but I bet that's just because it's by nature connected to the internet. More could surely be done with caching and pre-loading, but not sure if I want my computer to pre-load app store content all the time just in case I open it.

Compared to Windows it's of course absolutely unreal.