Out of the Big Three this Q4, I'd say MotB had the best atmosphere, Witcher the best story, while ME was the most "fun". Great game overall, and like I said before, I'd give all three of them a score in between 85-95.
Eden Prime: 2.5/5 - Yeah, it was a good intro mission with breathtaking backgrounds, but it kinda felt on the short side like it was missing something.
The Citadel: 3/5 - Generally, a well thought out idea with the classic cyberpunk sociological-infrastructure layer thing going on. Unlike Taris (K1), however, I didn't feel it was used to its full potential in terms of sidequests.
Therum: 1.5/5 - With the exception of picking up Liara (and Bioware's obsession with the Tower of Hanoi), this place was pretty much forgettable.
Noveria: 5/5 - One of the most awesome levels ever. This place had it all. The shift from corrupt sci-fi corporation busting to Half-Life-esque research facility ass kickery was totally sweet and awesome.
Feros: 4.5/5 - Another brilliant level. Kudos to the devs again. I was really digging the "cabal-of-crazy-cannibals" vibe I was picking up ala Jade Empire.
Virmire: 4.5/5 - Wrex, Ashley/Kaiden, Crazed Salarians...to say anymore would spoil it. Needless to say, this level epitomized the awesomeness of ME.
Ilos: 2/5.5 - WTF, Mate? Nah, it wasn't really that bad. But generally suffered from that inevitable Hack-n'Slash-to-the-end-Boss feel that most RPGs tend to suffer from. Probably less a fault of the devs and more of an intrinsic thing with the genre.