Least favorite: Janeway. But that's because of how the character was written, she was all over the place, being nice and sympathetic in one episode, and a right psychopath the next.
Kirk could be like that. There are times when he was nice and understanding then there were times he could be a jerk. In season three of TOS there are sometimes he seems to bite the head off of Sulu and Chekov for no reason.