There's Game Grumps, Paragon Nova (of UberHaxorsNova,) and plenty of others.
It all depends on the flavor you're going for.
If you want Minecraft, you'd do no better than the Yogscast main channel.
If you want snarky commentary without a real "Let's Play" experience, try NerdCubed.
I prefer Game Grumps and the Yogscast, but I keep tabs on most of the good ones.
Zack Scott (of ZackScottGames) has the best playthrough of The Walking Dead Telltale game around.
One of the members of Game Grumps also is in a BAMF of a band, Ninja Sex Party. Check them out. They're awesome. "Unicorn Wizard" is probably the best song to start with.