Any YouTube alternatives?

I think YouTube is one of those sites that are hard to find an alternative to. In terms of size and breadth of content, I'm not sure there's another service that can even begin to match it but I'm not the King of the interwebs so there may be a site out there that has escaped my knowledge! I know Twitch/Vimeo may come close but for me personally, I wouldn't put it in the same league as YouTube.
Does anyone know of any websites that might be a YouTube challenger?