For current T:
He's consistent in responding to emails--always replies in some way, nearly always within 24 hours, generally sooner.
He can take criticism and tries to improve as a result of it.
He gives genuine apologies if he's done something that upset me.
He pays attention to little details about me.

He's generally very prompt in retrieving me.
He'll let me go in for extra sessions if I need one and will generally have openings in his schedule.
He's honest with me if something I say or do bothers him (which bothered me at first, but now I realize the benefits, after ex-T and ex-MC not saying anything until they were really annoyed about something--T would let me know much earlier on).