Depends on which island you are wanting to dive from. On Oahu I would recommend Dive Oahu on the west side or Aaron’s Dive shop on the east side. They both have decent tours. Maui, definitely with Ed Robinson’s as they treat you as an adult and allow you some freedom not some newbee student. Maui is the best water in the islands from my couple years experience of living there and diving them all. Lahaina Divers up in Lahaina on Maui also offer a good hammerhead shark dive across the channel near Molokai and that is a nice tour as well but they have limited tours of those a week/month so check out that schedule. On the Big Island you could go with almost dive operator to do the night Manta Ray dive. It’s just as cool as all the magazines say it is and only 35 feet or so which makes it an easy dive. I never got the chance for the blackout dives they offer on the Big Island as those are water condition based and mine were cancelled/changed due to current conditions, but I hear great things about them. Biggest thing is to spend the time on the shop websites and call if you have any questions. All of the LDS on the islands were very friendly and helpful to those coming for a visit.