I haven't watched them in a while, but PeanutButterGamer does funny videos and he also has a game play channel.
I've watched DanTDM before, and used to watch his modded MC survival, but I haven't watched it in a long time.
I watch Markiplier sometimes as well, but a lot of people watch him.
I used to watch a lot of VenturianTale, but haven't nearly as much within the last few months. Their videos can be really funny though.
I also watch Ethgoesboom, someone who does game play videos but as if FNAF animtronic's were playing them.
That's about all of them I think. I usually just watch videos based on topic rather than YouTuber, but I do every now and then either look up videos made by a certain YouTuber or look up things done by a certain YouTuber. Pretty much all game related stuff though.
I also have a long list of Watch It Again videos...