FreddieW and CorridorDigital
Criken. Not too sure he counts, but he's got over 200k subscribers and gets mentioned on Kotaku all the time. So I think he should.
THIS. but he isn't big, but he does play with other bigger you tubers and for those of you who aren't enlightened he is a bit silly, but I'll be damned if he doesn't make me laugh. Right now i have to figure out what videos to post.
VideoGameDunkey for his comedic insanity and his awesome musicals!
AVGN because his reviews are enjoyable and we often agree.
V-Sauce because knowledge is power!