My list is not full of just mainstream users, mostly people that are underground type, the ones I feel deserve more attention.
Halo Canon- Shows very insightful things about the Halo universe including reviews for content.
ReviewTechUsa- Great commentary, and non-biased opinions.
MrRepzion- I discovered him when looking for Anita rants, he made me laugh. He also has some interesting opinions and rants about religion.
Whyt Manga- An artist with an online manga called Apple Black, shown in a site called Saturday AM. A place basically the American Shounen Jump or Shojo Beat.
Arbiter617- I am sure a lot of you guys know him. He is responsible for great Halo Machinimas.
MikeWB- a friend of Arbiter's, in charge of The Unsociables.
Angry Joe- Funny, meaningful reviews for video games. His opinions are honest and not biased.
Moonshine Animations- Great stop motion animations and figma reviews.
Glass Reflection- Great anime reviews.
Rocket Jump- great shorts, and their VGHS was pretty awesome.