I am completely indifferent to which team i'm on and who's on mine and/or the other team, makes no difference to me =P BUT for the sake of the majority I agree with a few points.
Auto-Assign only, always the best choice.
Admin Commands to switch teams, always another good choice. (i.e; players joining spec, so they can join the winning team after autobalance)- should just ask to switch.
Generally it would be nice for an admin to be able to keep the teams balanced to keep everybody happy.