I may be alone in this, but I personally feel that older GUIs were better than modern ones visually. I really and unironically think that IRIX, CDE, Win3, OS/2 Warp, and KDE1 look better than what has come after. Sadly, software has actually improved measurably in almost every other way (if you disagree, your memories are a bit rose tinted, cuz… uh… not hard restarting due to crashes is nice) and these GUIs are therefore somewhat unusable today. Also, other commenters are spot on. There are a ton of different WMs and toolkits and everything… and most of them require so much fiddling.

For full desktops: Plasma is great, but I personally dislike it for a reason I can’t put my finger on. GNOME is great once I install about 12 plugins, but then those break on updates, and I cannot stand the default GNOME experience. XFCE is “fine” but lacks some refinement. Budgie is on life support it seems. I haven’t tried enlightenment in a while. Never tried Deepin.