I think the reason most people don’t like the Savor line is it has a lot of soy, and not all dogs do well on that. (At least the adult versions do ... not familiar with the puppy one). That said, if your pup is doing well on it then no worries, go ahead and feed it. Since he didn’t do well on the Eukanuba, it might be worth comparing the ingredient list to see if you can determine what didn’t agree with him so you can avoid it in the future (you might not be able to tell though).
By the way, your vet is wrong about needing a specific puppy food. The Pro-Plan 30/20 chicken is what is called an “all-life stages” food, and is perfectly appropriate for puppies.