Mine: Tenchi

Already did. I didn't like him in TinT. Mostly how he strayed from his roots and treated the girls.

I've been a Mihoshi fan for awhile... but I must admit she's annoyed me before. I hate the scene in Tenchi in Love when she comes back from.. whatever she was really up to and starts whining cause she can't find Kiyone.

Kiyone on the other hand hasn't done anything to bother me.

Nothing comes to mind.

I think TinT would have been better recieved if they used new characters rather than old ones that people have a particularly close attachment to.

One thing I find interesting about Sakuya is that she managed to win Tenchi legitimately while not living at his house and not having any special powers - Haruna stole him outright while Mayuka still resorted force and bought him into a different dimension.

I could see the OAV adding girls indefinitely to the household (Noike, Tokimi imo, and Misaki arguably) as love interests while outside the OAV, they kept it to the core cast plus Kiyone in the Hasegawa novels. They even dropped Kiyone's interest in Tenchi from the novels and subdued the rest as continuities wore on - going so far as to pull Mihoshi out of the household in TU.

Nothing

If she did that, she wouldn't be Sasami anymore.

I don't really have a favorite character, so I guess I could grow to dislike a character that disrupts the group dynamic in a bad way.

For instance, I wouldn't have minded Sakuya if she joined the group rather than try to break it apart, but that was kind of the point of the story.