1. Thane+Mordin, joint winners due to interesting backstories and characterisation.
2. Garrus, who WAS my #1 in ME1, but due to being a bit of a 1-dimensional asshole in ME2, he's demoted.
3. Legion. Funny, interesting, unique.
4. Tali and Samara. Samara was interesting, but not enough was revealed about her.
5. Everyone else.
6. Miranda and Grunt, both are utterly boring outside of combat and useless in combat.