FWIW, it's a tough choice. Anguilla has some of the best beaches in the world, far superior to Cuba.
We liked St. Martin because you have two cultures and great croissants on the French side. I swam on the beach at Philipsburg for a short time and got out as the undertow was quite strong. I think it was just that beach that was the problem. I wanted to go to Orient Beach but my wife refused to go (she's not into nude beaches). St. Martin is more commercialized IMHO but great bargains on gold jewellery.