Youtube hands down. I know that makes me seem like a loner since youtube usually all your friends, you've never really met. Facebook is for the people you know, but you don't think are cool enough to be your 'friend'. If they were, you would be hanging out with them IRL.
+ Smosh, KassemG, TheGameStation, BlueXephos, Tobuscus, Vlogbrothers and more are all primarily on YT