Freetube is great. I just wish the UI was better about bookmarking playlists and there was some way to sync my progress across devices, including Android
Have you tried the GrayJay app? I've been using it to cast Twitch and youtube to my TV, Download videos, and its got polycentric which is some kind of alternative to youtubes comments for videos
I'm not sure, but you can login to youtube from the plugins and YouTube can sync the watch history its under sources > YouTube > provide YouTube activity.