GNOME 3 will probably be looked back upon as ahead of it's time. It implements a considerable amount of features with a single design language that's easy to read, recolor, and interpret to one's liking. On top of that, the flexibility it offered for touchscreens is unparalleled. It makes UWP feel archaic by comparison.

I also, curiously, like the Nintendo Switch's design language. I used to be a part of that scene a few years ago but fell off due to time constraints, but I remember the feeling of awe that I got from seeing someone recreate the entire Switch toolkit piecemeal with CSS.