I have owned both. Used both quite extensively. I prefer panheads. Better for slight adjustments/movement when glassing. You can also use the bridge of your nose to move laterally the panhead (when it is cold and you want to keep your hands in your pockets). Panheads are much much better for spotting scopes if you end up using the tripod with a scope. Again for slight adjustments when glassing. My buddy had both when using his 15X56's too - he also went with the panhead. I thought the ball head I used was also heavier if weight is an issue.
