Well I'll be taking my original team into ME2, which is Tali and Liara, but I can honestly say I like every character in the game, except Kaiden. Kaiden is a one-dimensional fucker and no mistake, everyone else has a few levels:
Wrex - Bad Ass but at the same time secretly worried for his people's future.
Liara - Utterly devoted to knowledge but at the same time socially mind-blank.
Ashley - Home-grown-warrior-which-has-lead-to-perceiving-anything-new-as-the-enemy but at the same time she's more of a guardian of what she knows rather than an aggressive bigot against what she doesn't.
Garrus - I'll admit I originally thought this guy was a total pussy and useless in a fight. Now I like him much more as I've had him in my team when I played a Renegade character, much more of Garrus' more interesting darker side comes out that way. His frustration about being forced into a restrictive security role bleeds over into everything he does.
Tali - My personal favourite character. She's torn between taking something of great value home for her pilgrimage, as is expected of her, and simply never going back, which seems to be a desire that grows every time you talk to her as she learns more and more about the universe outside of the flotilla.
Kaiden - "Oh I was horribly abused as a child but I soldier on.........for no particular purpose."
Also, besides Kaiden (fuck Kaiden), has anyone else noticed that all your companions are sort of a prince/princess character, deposed or otherwise?
Tali - Her father is the leader of her species.
Liara - Her mother was a well respected Asari elder.
Garrus - His dad is a C-Sec bigwig.
Wrex - Son of the last 'old ways' chieftain of the Krogans.
Ashley - Descended from the military leader of the First Contact war.
Kaiden - Spoon-bending migraine-milking douche.
Someone else mentioned the banter between the companions in lifts etc, I've not tried every combination yet but I have to say some of the best stuff comes from these combos:
Wrex/Garrus - Old man vs New guy, Wrex constantly rips into Garrus for being brainwashed by propaganda and not knowing the real facts.
Liara/Tali - A lot of information comes out between these two that you wouldn't otherwise find, and it also reveals Tali's fear of prejudice against her people and her relief that Liara doesn't have it, methinks these two become fast friends.
Ashley/Liara - When playing as male Shephard, oh the sexual tension and barely restrained loathing.
I have to say that this is probably the reason that Mass Effect is such a renowned success. It's not the great gameplay (it has that too), it's the fact that you will literally find something new every time you play it, I'm still kinda pissed off that I haven't found the way to convince Garrus to try re-try for the Spectres.
