So I had an entire day to think about this question.
And still I find it troublesome picking just one character.
I just go all mushy with Anders and love him to bits, but the Chantry incident was a bit of a freak out.
Fenris is just godly and hurrrr, but he has to stop being paranoid about mages.
So I'll just have to go with ..
BAM!!
Alistair
It's actually quite to my own surprise I'm picking him xD
Although I did like him the moment I saw him in Dragon Age Origins, he is more of a silent favourite. I can rave about Fenris and Anders, but Alistair .. he's .. I don't know, I can't quite explain it.
He has this thing that makes him so likeable to me.
Plus, his awkwardness and allround silliness, what's not to like :D
Although he was training to become a Templar before joining the Grey Wardens, and I'm not a huge fan of the Templars, he's alright in my book ;)
Tomorrow:
Day 3: Least favourite character