I would say MY channel, but I am not so crude.
But CGR, CGR Undertow, Gamester, MetalJesusRocks, NESComplex...the notables
Luigifreakout123 is really neat channel I found out because the kid lives in my same vicinity and got some press from the Retroware guys at the PRGE.
Those are the popular choices, but I'm not of the opinion that they are the best choices.
CGR - Mark is a funny guy, but I feel the majority of his reviews in recent years are little more than gameplay footage with flamethrower jokes. Very very high production values, but lacking in actual content.
CRT Undertow - Kind of the opposite problem. The rotating door of reviewers leaves some games covered by excellent reviewers, while other reviewers try way too hard to be Mark-clones and fail, especially Keven. Even so, I prefer Undertow to the main channel for actual useful reviews.
Gamester81 - Why does everyone like this guy?! If you made a drinking game out of every time he says "actually", you'd be drunk by the end of any video he does. He seems the ultimate poser - he owns an arcade machine, but it's a 2007 super awful 70 in 1 reproduction that run bad emulators. I've played one and can really tell you that it sucks. yet.....there it is in nearly every video like he's proud of it. Even setting that aside, what he labels as "reviews" are almost always actually overviews - like the last few minutes of unboxing vids jst without the unboxing part. He owns a lot of rare and expensive gaming items from history, but it's pretty clear he owns them solely to collect them, and not to actually ever play them. Also, he's pretty rude. Don't ever try and email him if you want a normal kind of response.
MetalJesusRocks - He's friends with Gamerster, but he is in fact a pretty nice guy. I don't have anything against him at all. Moving on.
NESComplex - Man, if only Gameseter81 was like this guy. He's not absolutely full of himself, puts together extremely likable content and knows what he's talking about all the time due to the fact that he actually bothers to check his facts. This is the kind of channel I can support.
Here's a few of my own suggestions.
rinrygamegame - Once you get over the fact that OMG A GURL (and I know a lot of gaming nerds can't) you'll realize that she has some pretty interesting things to say, albeit somethings said are obvious. As a woman, she focuses mostly on cutesy topics, but her videos are nevertheless worth checking out. Just go in with the same kind of open mind you'd have if it were a male presenter.
phreakindeephreakindee - Lazy Game Reviews covers 80s computer hardware for the most part. Very enjoyable and useful tips if you are looking to get into classic gaming from the PC side.
lukemorse1 - Luke is a highly likeable dude who is lucky to live in Japan, where there is evidently a treasure trove of Japanese retro hardware. I agree with nearly everything he says, and although most of everything he does are merely overviews, I respect that he doesn't mislabel things "reviews" like gamester81 does.