Most of the gaming channels I've watched over the years aren't the "top tier" ones with a lot of success. I feel like I kind of watch just regular folks who talk about their games more than anything. I've been a long time follower of channels like Ballinnick1982, TV and Lust, Stefs2Def, Dustin Kries, Benzo8686, MovieStarKitten, Petedorr. Stuff like that, and several others that had faded into obscurity by now. I enjoy watching newly formed channels, and channels with virtually no subscribers on occasion.
I used to love watching Retrocalypse back in the day, the guy had a impressive DS collection and was very informative and inspiring. Unfortunately a flood ruined his collection and he closed his channel.
There was this one guy, I think his channel is gone called "PlayaLives" or something like that, he was okay. I couldn't help but watch the video of his entire game shelf falling on him over and over. That must have sucked.
As far as overrated, I think most of them have been covered. Not a fan of SeeJayAre, or really any channel that's more collector oriented, or based on sheer size of collection. And while AVGN is overrated, I still enjoy it.