From the many discussions around "the best" cabana it seems that most people either voice for the low numbers of the cabanas due to the proximity of the food and bathrooms. Others seem to like the higher numbers because they are more remote and away from the noisier beach. We have had #9 for our last two cruises and just by walking past the other cabanas we hands down like it the most. Number one reason for us is the extra shade from the tree over the hammock and the slightly directed view for a more direct view at the ship that perfectly frames your view. My wife and I are going to try an adult beach cabana for our christmas cruise.
All that being said I think any cabana would be awesome. The concierge hosts from the ship helps with questions and assistance for cabana guests and you have the concierge bartender from the ship running drinks for you. On top that of that it includes all the perks like inclusions of snorkeling gear and bike rentals. No matter the number it is awesome.