Everyone has there favorite spots on IBSP or any other beach for that matter. You have to find yours too. The fish swim so the hole that is productive today this season, might not be productive tomorrow or next season.
In terms of accessibility....
If you will be accessing the beach by foot (as opposed to 4x4) then it almost boils down to where you can park and how far you are willing to walk.
The north end of the park tends to be less populated, but has few access points.
The middle, from the bathing beaches to A23 can get very crowded in season, but has many access points.
The southern end includes the pocket, inlet and N Jetty , but A23 is the last access point and the inlet is over a mile from there.