Sadie is huge fan of balls too! I spent $5 at Christmastime and bought a kids set of balls that was 1 football, 1 soccer ball and 1 basketball. I think the football is her favorite...she also has tennis balls, squeky balls...doesn't matter as long as she can chase it. Cincy, on the other hand, finds the fuzz of tennis balls most apetizing. She is often walking around with green fuzz in her mouth!!