Welcome, MVReliant! Where on Vancouver Island are you? (We need a good charter in Nanaimo, having lost a fabulous one to fire last year.)
I agree that a reliable and safe boat, with appropriate safety equipment, is the first imperative. But after that, I like the ability to get shelter from the elements (preferably an area with heat). A bench for tanks and gearing up that's at an appropriate height is a safety matter. And I'm a ladder fanatic -- one of the reasons I LOVED the Diver's Choice boat was because it had a fabulous ladder. The rungs weren't too far apart, and there were very good handholds all the way up.
Once you have given me a convenient place to put my gear and get into it, and a good way to get in and out of the water, and someplace to get warm, the final thing I want is a captain who knows the dive sites and when conditions are right to dive them. Being put in the right place at the right time is the recipe for a good dive!
Helpful dive crew is awfully nice as well -- just somebody to help with the little things, like uncooperative fins or twisted straps. The ability to have a hot drink after a dive is welcome, too.