Discovery is probably the only reason why I still use YouTube. If somebody could make something that provides a non-Google recommendation system with tools to categorize/organize the videos I've watched/want to watch, that'd be great. Assuming the UI is at least on par with Google's, I'd switch in a heartbeat. Not that their UI is particularly good, but the alternatives I've seen (like PeerTube) are frustrating to use on a basic moment-to-moment level.