My prior GSD used to like these Slingshot Balls:
Pro Ball Go-Frrr Slingshot-Action Dog Fetch Toy, Double Play Kit
The squeak & light balls referenced below are a favorite for my current 14-month GSD . They bounce well. I have used these mostly in the house, for a game I call "balls on the wall in the halls". As an alternative to playing outside, I bounce several of these balls on the hall walls & between the hall & kitchen. I haven't figured it out, but Cassie hasn't destroyed any of these balls, and I leave them laying around and available for play (in multiple sizes). The lights have a limited life, but they still bounce & squeak, after the light fails. She generally gives more attention to the smaller ones., for some reason. I've tried various outdoor ball games (with other types of balls), but Cassie hasn't shown much enthusiasm yet. At some point, I may take some of the Squeak & Light balls outside. With shorter days & bad weather ahead, I'll likely reserve these balls for indoor play.
Gnawsome Squeak & Light LED Ball Dog Toy