My all time favorite YouTuber is Pewdiepie! I have been watching his videos since early 2012 and is actually the first YouTuber I started watching regularly. He never fails to cheer me up on a crappy day.
I also watch grav3yardgirl, Thoughy2, TJ Kirk, The Slow Mo Guys, Vsauce, Dogumentary TV, CrazyRussianHacker, BlastphamousHD, and Exploring with Josh. I may occasionally watch Shane Dawson, but not a whole lot.