I agree with Angel's Vision. Mind Control would be like walking up to a vampire, saying "You're going to not put up a fight", and then staking them. It wouldnt be interesting. And spike and angel are the last people who need mind control, and riley would have been just boring. Xander would be interesting, but as said before, only for an episode. But then that would seem a lot like Earshot, and we dont want that do we? So...none.