More that most things, “stage lines in a file" is the killer app for any git GUI. magit being the one I use, but any of them can be amazing in those surprisingly frequent cases where you want that.
@offby1 @jacob @carlton I could extol the specific virtues of magit above and beyond this, but it gets into emacs esoterica pretty fast, because you need the ideological predisposition and prior reading to understand why you want "motions" and a keybinding grammar which, like, most people demonstrably don't care about. but "select with mouse rather than hand-computed row/column offsets" is a pretty common desire these days, in 2024 I think we can say that line-oriented editing lost that war