Dotted with numerous idyllic tiny islands, the Caribbean offers a wide array of dive destinations. I'm managed to visit a fair number of them, and it's fair to say that there's something for everyone in the variety of diving as well as the top-side vibe of the many different cultural mixes to be found in the Caribbean.
My personal favorite is Bonaire. It's the one place I keep going back to every couple of years. It's not just the top notch diving, but also the whole atmosphere you get to enjoy staying at Captain Don's Habitat.
St Croix is probably the place I'm most looking forward to going back to some day. The diving I enjoyed there was fantastic, and I believe I didn't get to see some of the best sites the island has to offer. While Cozumel doesn't really do it for me, the diving is good, and if you're looking for adventure, the nearby Mayan ruins and cenotes offer lots of opportunities for an extended holiday.