I voted for this a while ago, but I'm pretty sure it was for Faith.
I absolutely loved Cordy throughout Buffy and and the first 2 episodes of Angel, but she started to lost her spunk and I really got tired of her.
Whereas Faith was excellent throughout all. She had spunk, attitude, whatever you want to call it. Even after she stopped being evil, she still had the same character, and didn't end up all broody and sorry about what she'd done. She was sorry and you could see that, but she knew that what she said, didn't matter half as much as what she did.
Even in Judgement (i think) when Angel went to see her, she was still the same Faith! Joking about with Angel about him singing Mandy!
phew, sorry about the babble