Sponsorblock can skip sponsors, self-promos, subscribe reminders, intro animation, and end credits. (crowd-sources the timestamps)
I'm currently happy with NewPipe - which is essentially a youtube-dl GUI, and has to be updated just as often, which is damn annoying because FDroid is still completely broken UX-wise - but I have less tech-savvy people around me, who would very much like an alternative to the official YouTube app.