Favorite: Not giving them numbers since I don't think I could compare...
Tali (Her whole romance bit is just... adorkable. I'm a sucker for shrinking violet characters, and for some reason, giving her a Claymore shotgun in ME3 and watching her take down a brute just made her hotter. And that)
Joker (Brittle bone, and yet one of the most badass characters, and excellent work voice by Seth Green)
EDI (I'm a sucker for deadpan delivery. "That is a joke", AWESOME.)
Garrus (I'm Commander Shepard and this is my favorite wingman in the citadel... )
Mordin (I am the very model of a scientist salarian,
I've studied species turian, asari and batarian.
I'm quite good at genetics (as a subset of biology)
Because I am an expert (which I know is a tautology)
And advice on how to sex Tali safely (avoid ingestion).
And the way he just died... MORDIIIIIIIN!! ;_
Honorable mention to Thane, just for that sequence where he kills that Asari whose name I can't recall.
Best Villain: The Illusive Man, Martin Sheen is an amazing voice actor.
Least Favorite:
Javik (too angry)
Liara (I grew disenchanted with her when I saw her channeling Benezia.)
Kai Leng (He was doing fine, until he sent me that taunting e-mail.)
Jacob (So boring.)
Kelly (Shut up, Kelly.)