We've got two active dogs. A Pit with a sensitive stomach and a mutt with a stomach of steel. They were both on Natural Balance, but the relatively low protein meant we had to give the pit too much to get her what she needed. The fiber just tore through her. The little mutt was fine on it.
I went to a local pet food/supply store and the guy recommended one of the high protein diets. We opted for Blue Buffalo Wilderness. Our pit's stomach issues are gone.
We actually used to feed the pit a raw diet. Chicken, turkey, sweet potatoes, cottage cheese, yogurt, eggs, etc, but it became a nightmare with the addition of the second dog. I was spending every other Sunday chopping up whole chickens and boiling sweet potatoes. I'd love to go back to it, but the amount of food the pit went through was staggering for a 55lb dog. If she wasn't eating close to 2 pounds of meat and another pound of potatoes daily she'd puke bile because she burned through everything already. Since they were eating only fresh human food, and meat at that, our dog grocery bill was over half of ours. It was hard giving it up though.