On a cruise with Holland America in late February/early March, I dove with Happy Divers on Aruba and Bas Harts Diving on Curacao.
My wife and I went with Happy Divers because the ship didn't arrive in Aruba until 1:00 PM, and they were the only dive op who would do a two-tank dive in the afternoon. Their op is very small -- a Zodiac that holds about 6 people and gear. They did their best to provide a good experience. The briefings were good and the DM did a good job of guiding. My wife and I were a little disappointed in the first dive on the Antilla. The viz was poor, there was little marine life and most of the wreck is just twisted steel and hull plates. The second dive, Arashi, was much better -- better viz, better coral, plenty of fish, eels and a couple of turtles. Going back to the dock was a long, bouncy, wet ride. Once there, they were great with dockside service, even rinsing our gear and wetsuits.
There is a reason why Trip Advisor ranks Bas Harts Diving as the second best water attraction on Curacao. At first, I was suspicious when I saw that all but one review had given him "excellent" rating. The dissenting one ranked him "very good." He is beyond a doubt, worth every accolade. First, he was waiting for me at the ship when I got off. My wife was coming down with a cold and decided not to go at the last minute. No problem, Bas loaded my gear and off we went. Driving from the dock to the western sites was a tour in itself, with Bas pointing out numerous features of the geography and history of Curacao. He was very willing to stop for a few "photo ops" of landscape, flamingos and an old, abandoned plantation house.
Both dives were shore dives. And, Bas is super prepared for the rocky coast, rolling out woven mats to lay out gear and stand on while getting into wetsuits and BCs. His rental gear is in top shape, too. He buys new every year. (I usually like to bring our own, but decided to leave the BC and reg at home for the cruise.) The dive briefings are very thorough and prepared me for shore entries and exits.
Both dives were excellent. I was very impressed with Curacao under the waves. Lots of fish and large ones, too. It reminded me of what I used to see on Grand Cayman before the lionfish arrived -- large schools sergeant majors, French grunts, snappers and lots of parrotfish. We saw turtles, a large slipper lobster making its way through the coral, spotted eels, a very large porcupinefish and more spotted drums than I have seen in a long time. The only bummer was my camera, which decided not to fire its strobe after my test shot. (Bas even helped me troubleshoot that issue.) But, even that was not a bad thing. Bas also brings his camera along. For once, I was not just the one behind the camera, but got some very nice shots of myself and assorted sea life. Bas is a very good photographer.
The bottom line is that I think Bas Harts Diving is about as good as you could possibly ask for when it comes to diving on Curacao.