I've been lucky enough to find a vet that is perfect for me.
Honesty has been a huge plus from him, when Arthur and Chester came down with hepatic lipidosis (unknown why) he said that he would be happy to refer me to a vet who had more experience with it and the things that it required (feeding tubes etc.), I stayed with him and he was great throughout the entire process.
Another big plus for me is that he'll tell me what's going on in medical terms, but can explain any big words
Another thing is that I can bring one cat in and ask questions about all my other animals and I don't feel like I'm being a pain in the butt and that I need to hurry up so they can get on to the next person.
People skills is pretty great too, but I'd give that up if the vet was really excellent.
I think the biggest thing that I appreciate about my vet is that when I get home and think about everything he's told me I don't doubt what he's said. I've had vets before that (when they're not saying "I dont know") have told me things that I just don't believe.