I just moved out here myself, and can speak to a couple of places. I too will put in a plug for Gabe and Drew at Kaimana. Great operation, they dive all over the island, are supportive of more advanced divers as well as vacation divers, and offer a really solid club membership. And generally speaking, I can't say enough good things about their people--they're all guys and girls you look forward to diving with.
I've also had some great dives with Island Divers, and particularly liked diving with one of their DMs, Nate. Because of the size of their operation, they have some unique pros and cons: my experiences there have been more hit or miss depending on who's running the dives that day (hint: don't buy nitrox only to be told later you need to surface at 1800psi because the OW students have to come up), and seem more tied to dives easily reached from Hawaii Kai as opposed to going to different places as often. But they have a great dive and air club, and they support more gear configurations (e.g., their pro-valve tanks are DIN friendly, they offer O2 cleaning, have a decent selection of tech gear in stock, and have good gas blending facilities on Hickam if you like HP tanks filled to actual capacity).