Donna's had one funny moment imo when she wanted to nominate everyone for eviction, but I agree with you that other than that really she hasn't done that much.
I am oddly starting to like Jack, sometimes it almost feels like it's myself in the house with some of the stuff that he says in the Diary Room, and his general demeanor towards some of the neurotic people that are in the house.
Admittedly I kind of struggle to really register anyone else, including Danny controversially.