Some dogs like Kongs, some don't. Mine don't pay any attention to them unless they are stuffed with food. Daphne the Destructo-Rott has the black "indestructible" large Kongs in pieces in less than an hour.
He's your dog, you know what size would fit him best. If he doesn't like it they have a 100% money back guarantee.
Cooper The WonderDog
Daphne The Destructo-Rott