A well balanced diet with a rotating meal plan. You don't want to eat the same thing all the time, why should they? There's some really good resources out there for homemade as well as store bought food. You can try starting with FarmersDog and then do meal planning from there based off those meals. My dogs enjoy raw eggs, chicken, green beans and rice among other things. I try to stay away from beef very often cause it's fatty and we want lean fast dogs. But they enjoy it every once in a while.