Who is it? I don't mind multiple answers, as it is a little hard to choose a favorite:).
Personally, mine is 'Algol gaming' (His channel can be found http://www.youtube.com/user/AlgolGaming) He is not a very big YouTuber, but I enjoy his videos very much. He mainly plays minecraft (go figure), so if you are not into minecraft, I recommend you don't watch his videos.
Feel free to leave your comments, and leave a channel link possibly:)?
I'll play the role of the little fanboy, but I was coaxed into buying minecraft by watching BlueXephos videos. Now I know we've all heard of them and I know they're certainly not the only group out there who makes interesting minecraft videos. My picks would have to be Uberhaxornova, CaptainSparklez, and DeadWorkersParty.