My favorite HAS to be Kikoskia. While he does a LOT of long LPs (Quite a few are over 100 videos long, but are mainly older DOS RPGs.) He does have some interesting ones on there.
On top of that, he'll randomly do some really short/stupid/hack games, just to make fun of them. Such as the Barbie games, the Barney game, "Mortal Kombat 5". My favorite LP of his is his X-Com one, which he has 3: Terror from the Deep Pacific Challenge (Single base, in the WORST possible location), X-Com Superhuman Antarctic Challenge (Same thing, but with the original and on the hardest difficulty. And Let's Play X-Com again, without any specific challenges. He also taught me how to play those games (not personally, but I learned by watching the LP.)
I also like Necroscope86, though not as much. His LPs seem to be really hit or miss. I liked his Toonstruck and I Have No Mouth and I Must Scream LPs, but that might have something to do with those both being games I've wanted to play, but haven't been able to play.
Deceasedcrab also has his moments. I like his "Do an LP while still high on the effects of dental surgery." Every time he gets a filling or something, he does a short LP while he's still feeling it... while having a mouth full of Gauze. It makes him sound a bit like Brak from Space Ghost. He also does some indie games which can be interesting. He doesn't update regularly though. He will do an LP, with and episode every other day, than drop off the Earth for a few months before doing another one.