My wife and I just got back from a week in Kona. After all the positive comments here at SB, I decided to go with Kona Diving Company. At the risk of sounding like a paid shill, I can honestly say they're the best op I've ever been out with. We had 3 different DMs on our 3 sets of dives, and interacted with several others. Every one of them was enthusiastic, personable, and helpful. Our DMs pointed out all sorts of things I never would have found, including several nudis, a harlequin shrimp, and our first ever frogfish. Very thorough briefings, including notes about the types of fish we could expect to see. And a nice 4 to 1 diver/guide ratio on our morning dive trips (6 to 1 on the manta dives).
There were a few things that separated KDC from other ops I've been with. Most importantly, the crew seemed genuinely happy to be out there, and that showed in their interactions with guests and each other. They also rinse your gear for you and store it at their shop until your next dive. And they provide really good food - wraps between dives, brownies after, and trail mix and gold fish whenever you want them. Plus water, fruit juice, and soda.
The crew at the shop deserves mention, too. We had a big swell come through mid-week which resulted in the cancellation of our manta dive and then our re-scheduled manta dive. The folks at the shop worked hard to get us re-scheduled on a night that was initially booked solid and kept in constant communication with us regarding whether or not the conditions would be appropriate for my brother and his wife, who were interested in doing the trip as a snorkel.
James