To me, "favorite" means the one that makes me the happiest, as a character. Like when someone asks me what my favorite movies are (which ALWAYS happens, every time I mention I majored in film studies), I'll usually say Casablanca and Amélie, and sometimes Singin' In The Rain -- all great movies, but I'd be reluctant to say they were the BEST, per se. They are my favorites, though.

I voted for Keith Mars -- I like him a lot as a person, I like his style as a parent, I like that he was always there for his daughter, that he worked really hard to make her happy and successful. I like that he's not perfect, and that his daughter's still kind of messed up even though he tries hard to balance it out. He just makes me really happy -- in a deep and abiding way, versus the cooing I do over Danny or Castle, or the interest I have in Bob Fraser or Walter Bishop.

I don't know what "favorite" means to you, but that's what it means to me. Does that help?