I'm hesitant to say
farfromsubtle/FFSTV/VGA/Video Games Awesome/Fraser Agar since they're not really YouTubers. (But they are god damn machines, they push out at minimum one episode per week but often more than that. One episode is commonly 1-5 hours long.) They're doing their own thing and YouTube just happens to be a popular place to upload videos.
Same goes for
SpoonyOne/Noah Antwiler but his videos are mostly reviews. He's made some of the funniest videos I've seen. Some of his Counter Monkey stories are hazardous for ribs if you actively listen to the story.
A more recent favorite of mine is
Lindybeige. His videos of olden time warfare make my reference boner diamond hard.
scholagladiatoria makes videos similar to Lindybeige but I haven't had the time to check him out yet. I'm sure I'll love 'em though.
Then there's
Brady Haran with his million channels.
Extra Credits is great for anyone interested in game development, including artists and programmers.
Then there's the super popular channels like CGP Gray, HAWP, and AgentXPQ.
