I will pass along my experience with Science Diet. I do a fair bit of rescue work with our county shelter, very often times, puppies. The shelter feeds Science Diet and provides this food when people foster puppies. I choose to feed the puppies I pull Pro Plan, which is what my Lab puppies get.
I am knocking wood as I say this but the puppies who are fostered by others who choose to use the SD don't look as good as the puppies I foster. The weight is not there and very often litters are not healthy enough to fight off viruses such as Parvo. My guys are exposed to the same things in the kennel that these other litters are but seem to have the strength from good nutrition to fight off some of this stuff.
