Well, shiet. Ninjas everywhere!
Gaming related, Game Grumps [https://www.youtube.com/user/gamegrumps?feature=results_main] is alright, but I prefer Egoraptor [https://www.youtube.com/user/egoraptor?feature=CAQQwRs%3D]'s and JonTron [https://www.youtube.com/user/JonTronShow?feature=chclk]'s individual channels. Both channels are mostly humor with a dash of game design discussion. Egoraptor's Sequelitis in particular is pretty interesting. Game Grumps on the other hands is mostly them making homoerotic jokes at each other and laughing their asses off. Game Grumps VS is the worst, with Jon complaining nonstop even when he's winning.
RoosterTeeth [https://www.youtube.com/user/RoosterTeeth?feature=chclk]'s Achievement Hunter has some fine folks, my favorites being Michael, Gavin and Ray. Geoff has his moments too, when he's not being a grumpy prick. He does his best work with his 5-ish year old daughter, Millie. I've also heard that his laugh can cure cancer, but that's still being tested.
Achievement Hunter puts out a crapton of stuff daily, most of which is pretty much fluff. Their let's plays are alright though. Michael [https://www.youtube.com/user/LtMkilla/featured] has his own channel where he also does let's plays and such. If Michael is too obnoxious for you, Gavin [https://www.youtube.com/user/theslowmoguys?feature=CAoQwRs%3D] has a channel where stuff gets broken in super slow motion. The man is an endless fountain of entertainment. Ray is usually just kind of there, waiting to make a precision strike at your funny bone. I don't think he has his own channel though.
Then there's TheSw1tcher [https://www.youtube.com/user/TheSw1tcher], or Two Best Friends Play. I've seen all their stuff, and they haven't failed me yet. Go watch them. Do it now.
There was a time when TheAmazingAtheist [https://www.youtube.com/user/theamazingatheist?feature=CAQQwRs%3D] was alright, before he turned into an angsty teenager.
TotalBiscuit [https://www.youtube.com/user/TotalHalibut?feature=CAQQwRs%3D] makes StarCraft 2 commentaries sound amazing. 'Nuff said.
Those are the ones I watch regularly. Well, except for The Atheist, whom I just can't stand anymore.