Well, TheRunawayGuys [https://www.youtube.com/user/TheRunawayGuys] are always one of my top picks. Together, chuggaaconroy, NintendoCaprisun and ProtonJon have this wonderful chemistry. Chugga and Jon always find some way to irritate the other, but you can tell that it's all in good fun, and CapriSun never fails to bring a smile to my face. I like all of them individually, too.
I also like versus [https://www.youtube.com/user/versus]. For those who don't know, it's a collaboration channel between JoshJepson and AttackingTucans where they play games and try to 100% complete it first. I like both of these guys, but a word of advice; While he's gotten better, Tucans has a tendency to have moments of loudness and some off-color commentary. So if you find that stuff irritating, off-putting and unfunny, I wouldn't recommend his solo LPs. (I don't mind, though)
I can never go wrong with PeanutButterGamer [https://www.youtube.com/user/PBGGameplay]. I actually like him more than JonTron. (Heresy, I know) His Collection series is just enjoyable overall and leaves me in stiches, as well as making me feel all warm and fuzzy inside. His videos are so comforting. And his Hardcore series? One of the best series in Youtube, in my opinion.
Let's see...someone who might not be as well-known? KoopaKungFu [https://www.youtube.com/user/KoopaKungFu]. Like PBG, his Let's Plays are also very comforting, and I think he's quite funny. I find him very underrated.