I went KDE Plasma. It works pretty well, it feels close enough to Windows that the transition is as painless as possible, and it's got tons of advanced tweaks for power users. GTK and Qt apps both seem to run fine under it. Most importantly, it gets out of my way and lets me work.
(Other alternatives I enjoy include Cinnamon and Xfce. I cannot stand gnome-shell, it's like a tablet OS or something.)
Lots of popular distributions support KDE out of the box (Kubuntu, openSUSE, Fedora KDE, etc), and it'll install on pretty much anything else with minimal fuss. That's the most fun part about desktop environments on Linux: you don't have to pick just one. You can install a bunch side by side and switch between them when you log in. Once you know this, it becomes fun to experiment :)
(Other alternatives I enjoy include Cinnamon and Xfce. I cannot stand gnome-shell, it's like a tablet OS or something.)
Lots of popular distributions support KDE out of the box (Kubuntu, openSUSE, Fedora KDE, etc), and it'll install on pretty much anything else with minimal fuss. That's the most fun part about desktop environments on Linux: you don't have to pick just one. You can install a bunch side by side and switch between them when you log in. Once you know this, it becomes fun to experiment :)