I'm far from being an expert on food, but based on the amount of reading I have done, I agree that it is the quality of food that you feed your little one that matters most and whether it suits him/her. I have been feeding my little one Innova EVO for a while and he has less loose stools(sorry, sounds gross), we also give him some steamed sweet potato for extra fiber. It works fine for him, but I think all dogs are different. Stick with high quality foods and work from there. Our vet said that it takes a bit of trial and error with different foods. (FYI: We are still waiting to see in the long run(3 months) if this food improves his health.)
Good luck- finding a good diet is a difficult task!
P.s. Vets don't seem to know what brands are good here either. I find it strange as I'm a scientist and would be more careful myself.