I know what you mean, I have been to some really wonderful beaches in different countries, and if you are just talking about the beach itself, I have been to some that are in my opinion better than Negil. However, the beach is just one aspect. While I have found more secluded, and more "naturally beautiful" beaches, the food, music, and general vibe were less impressive. Also, none offered the beach/cliff experience like Negril does.

Negril is unique onto itself and while there may be better beaches physically perhaps, when you group everything that makes a visit enjoyable, Negril comes out way ahead of a lot of other beach destinations.