Great info here! We've had good luck with these over time:
"JW Pet iSqueak Bouncin' Baseball Dog Toy" - in fact, it was Xapa's current favorite.
We tried the tennis style balls but they got destroyed pretty quick. The "Chuckit!® Ultra Ball Dog Toy" is pretty durable but heavy and you have to be careful as it could hurt your dog if they caught it from a high bounce. Also, it doesn't squeak.
Based on this thread, I just placed an order for 2 of these in anticipation of our new puppy in (hopefully) 2 months & 1 week or so:
Latex Squeaky Ball Toys for Small & Big Dogs