I do agree with the informative let players being the best. As such, even though my girlfriend disagrees, I find the fact that Game Grumps don't read the instructions somewhat annoying. I do like JonTron, but he's more of a critic, I guess.
Strangely enough, and against my better judgment, Achievement Hunter/Let's Play channel are my absolute favorite LPers. They are of the 'swearing idiots' category, but it seems that at least one of them can play any given game adequately, they mostly know the instructions, and they do call each other out when they get too dumb. The swearing leaves a little to be desired, I kinda wish I could watch with my little sister. But the thing that always gets me is that they either fail epically, or have a huge win that makes me cheer with them. Its a great reaction I don't get from much else ^^