Starmark Everlasting Treat Ball Dog Toy [amazon.com]
I've got an English Bulldog and a French Bulldog, both aggressive chewers and the English Bulldog has yet to even leave a mark on this toy.
I've tried Kongs, I've tried Nylabones, BusyBuddy Jack, all of them they chewed down to a nub, but this everlasting treat ball is great.I only bought an extra to take to my moms house and saw it's on sale for $14.99 I originally paid $25 at Petco
Don't get me wrong the treat disc lasts about 20 mins, but they love just gnawing on the empty toy for hours.
The large is pretty big and it doesn't roll around everywhere so I'm not constantly digging it out from under the couch.
Amazon's price was cheaper then my local Petco, so it's a good deal for me at $14.99 and it's actually on sale, down from $24.99.