For years I’ve been using
C-x u (undo) for undo. As much as I use it, though, I really need to get
C-/ (undo) under my fingers.
I never remember
revert-buffer, since I rarely get myself to the point where I want to just nuke everything from orbit—so perhaps it’s not surprising I rarely think about it.
In fact, I think the interface of GNU Emacs’ undo facility is one of the few places where it falls dramatically short of its potential. I really don’t know what sort of facilities that other editors have, but given the way that Emacs stores the history, I’m surprised that the baked-in functionality provides no way to access it more efficiently—I mean, there’s not even an explicit redo command, you have to just undo your undoings, ad infinitum. I’ve often accidentally started redoing things when I hit an injudicious key, etc.