Vimeo's there, but its even more curated/niche. I've always liked it more, but it hasn't had the same massive growth/traction (and to a degree I think they want it to stay that way).
Year ago many people tried to make other sites (Viddler, Blip, etc) but most/all of those folded for various reasons. I do wonder if someone today could do better...
Vimeo, for me, is for saying "Vimeo can't play on your setup" because it doesn't recognise the user agent or somesuch, so doesn't even try.
I once heard the two characterised as "youtube will always start to play, but the quality can stutter, whereas Vimeo is smooth as butter... if you can actually get it started in the first place". Even on machines for which Vimeo doesn't exhibit my problem, it doesn't always start for some reason...
Year ago many people tried to make other sites (Viddler, Blip, etc) but most/all of those folded for various reasons. I do wonder if someone today could do better...