My husband & I went to Cayman Brac in July of 2000 and had an amazing time. The dives there were awesome. The reefs were very 3 dimensional with lots of cool sand shoots and swim throughs. Animal life was not very large but plentiful. Very healthy reef systems. We stayed at the Brac Reef Resort. It was a great operation. All inclusive with meals (breakfast, lunch, dinner) Very tasty meals. The dive operation was great too. Talk about getting spoiled...when you arrive they tell you to leave your gear (masks, fins, snorkels, regs, bcs) in front of your room in the mesh bags they provide you and someone from the dive shop will come by and collect your gear and bring it to the boat. That is the only time you need to touch your gear outside of using it for your dives until you are ready to pack up and leave. The first morning you are supposed to dive, you just go down to the dive shop sign in and head over to the boat and your gear has magically appeared and all set-up with tanks for you all ready! All you have to do is get on board and relax. Then when you get to the dive site (which is only takes a couple of minutes for majority of the dives) you walk to the back of the boat and take a seat, put on your fins and your gear is carried...yes I said "it is carried" over you and placed on your back so you can strap it on and you're set for your giant stride! THEN...once you come out of the water, they take the tank off at the back of the boat and they carry it back for you!! It's amazing when you get so spoiled!!! And when you get back on land, you leave all your gear on the boat until the next dive. And after your last dive of the day they tell you leave your gear on the boat. They take the boat and park it somewhere and it magically appears again in the morning.
As for Belize, I can't say how it is yet because we haven't done it yet but plan to do it this April on the Nekton Pilot, a live-aboard instead of on land. Reason we decided on this was because we heard from others who've been to Belize say that other than Turneffe Island, it's a long boat ride. The one person I know who stayed at Turneffe Lodge said it was heaven and they loved it. But our choice for selecting a live-aboard was because everyone says it's the easiest way to dive. However, I was relunctant to try just any live-aboard until I heard about the Nekton cruises and their SWATH technology which is supposed to make the boat more stable than other live-aboards. So I was convinced enough to try it..we'll see!
Good luck on your decision! And if you want to know more about the Brac Reef, just let me know!