Is Famous Vincent the best? Well, that is subjective but I've never heard a negative review. Most people just hang on the cliffs and wait for him to come by and arrange their excursion. Or you can go to the front desk of your hotel and they can make arrangements. Here is some info I found on google. His phone number is right on the boat.

https://getmyboat.com/boat-tours/riv...jamaica--74852

Most glass bottom boat operators do not have an online presence or reservation system (save for Sun Baby, who is also very good). Small businesses in Negril are very old fashioned.