For anyone wanting to dive in Maui, and will be out by Lahaina, I would try Lahaina Divers. Very professional, have the best type of dive boat, and all around was one of the better dive trips I have been on.
Make sure you get out to the Cathedrals, as its really one of the best dives there. Also, dive the back wall of Molokini Crater if you are skilled enough for drift dives.