My favorite "GUI" is just text. The shell interface is, for me, the best [1]. It's very rarely ambiguous, and it works well for many people, even people without vision.

[1] https://nixpulvis.com/ramblings/2018-07-11-building-a-shell-... [1b] https://www.linuxjournal.com/content/without-gui-how-live-en... (also on the front page right now).