Quality and Consistency
Dunlop Australian Open ball has a consistent bounce and long lasting felt albeit it feels a bit hard and heavy on the racket. I think because it is made heavier and pressurized higher for modern string and racket to slow down the pace. Penn ATP and Dunlop ATP are two softer balls and easier on the arms, but the first one has inconsistent bounce, and the felt the second fluffs up too much. I usually open the can of the Australian Open ball one week before I play and it has good bounce and feel.