When my obsession with POTO was new and a lot more exciting, Emmy Rossum's Christine put me in awe every time I heard her. But now, I kind of dislike all the Christine's in all the POTO movies I've seen. Rossum is still probably my favorite of them all, though. (The worst one was in the mini series, she freaking black mailed Raoul & Erik saying "If you love me you'll do this. If you love me you'll do that.")
I used to hate Raoul, but that was just because I didn't want to see Christine go off with him. He's not a bad character. In the movies, anyway. He really got on my nerves in the book.
And while most people dislike her, I love Carlotta! If she were like someone I knew in real life, I'd probably hate her. But her character is such a....well, a character! Her high and mighty personality is so unreal, and I get a kick out of her.
So I think that my least favorite character would be Joseph Bouquet. Freaking perv needed to mind his own business.