Ubuntu (gnome):
Kubuntu (kde):
Budgie (for OSX fans):
Mate (lightweight for raspberry pi etc):
Studio (with all the audio/video/graphics/publishing multimedia production software - they will use KDE instead of XFCE after 20.04):
Xubuntu (Xfce):
Kylin (for those Windows UI fans who don't want to put up with the lack of productivity in Windows):