I'd say it's between Crim, Sora, and Silver Knight. I like a lot of the other cast members, but I basically see them every episode, and some of the charm wears off halfway through the show with them. Crim is a hero who lives and dies by his morals, Sora is a childish backstabber, and Silver Knight is the soldier who overreaches his authority but has good intentions as to why he does so.
I also really like Macha because she is a great portrayal of a silent character. Actions speak more than words.