Coz - Dive Paradise, three times. They get a bad rap, but we've always gone out on the small boats on the afternoon dive and have usually had the boat and crew almost to ourselves.
Grand Cayman - Aquanuts, twice. First time we did Trinity Caves and the Aquarium off of Seven Mile Beach. The next time they had moved all of their boats to the other side of the island ahead of Hurricane Georges and we got to dive Main Street on the North Wall and another nearby site - fantastic!
St. Maarten - Forget the name of the operator, but we had to walk a long way to their shop, they only did single tank dives, and your boat was a kodiak. Decent wreck/reef combo dive though.
St. Croix - Cruz Bay Watersports. Nothing fancy, fairly small boat, OK divemaster.
Barbados - High Tide Watersports, twice. I highly reccommend Willie Hewitt and his staff. He will pick you up and return you to the pier, and they are all very friendly and professional.
Aruba - I've used the ship's operator, Red Sail Sports, twice here. They bring the dive boat close to the ship and take you to two awesome wrecks, the Antilla and the Pedernales.
St. Thomas - had the worst dive experience ever with the ship's tour, who was using Dive World, at Coki Beach. I'd like to try Sawyer's but we usually visit St. John on this stop.
Curacao - Underwater Curacao. A last minute decision to dive. Nice folks, good diving, but rental gear was in pretty bad shape and they weren't very organized.