We use Purina Pro Plan Small Breed Puppy Formula. We raise Poms and they really seem to like it. Sometimes we have to get some wet food and mix just a teeny tiny bit in just to get them going and slowly wean that out of it.
If you keep the cat food in one place for long enough, the cat WILL eat. You just have to be more stubborn than the cat, I know it's hard! Put up a gate that the dog can't get over or your puppy will eat the food forever. The puppy wanting to eat the cat's food is a case of 'the grass is greener on the other side' syndrome. There are better foods out there than purina puppy chow yes, but swapping your dogs food any time he decides he wants cat food even more isn't going to help heh
He only wants it because it's someone elses. Put the cat food up high and don't worry, the cat won't starve. When I dogsit, Layla ALWAYS goes nuts for the other dog's food, even if I put her own food in the other dog's dish. It's just "I want what he's getting!".
I would move the cat food to where the cat can get it and I would use the Purina pro plan small breed puppy food, or at least some other good small breed puppy food. They will both eat when they get hungry enough.
Go to the pet store, not the market for dog food. I feed Naure's Recipe, Nutro Natural Choice, or Royal Canin holistic recipe. I feed all dogs, regardless of age, puppy kibble. If they tend to get fat I measure out less food. These are Labs. Real pigs for eating. With small dogs you would need some additional advice. READ the label. If you won't eat it...be careful. Don't feed food w/ preservative, other than vit. e&c. Check the label for the freshest bag on the shelf. Ask the store owner to get fresher bags, if needed. I think their distributer changes them for free? They don't seem to mind. Dick Van Patten has a nice food. Oh, THE BEST is Nutro Ultra. It is pricey, but I give it to pups. Has acidophilus in it and keeps the stools firm, even at the dread 6 wks.Real small kibbles. Highly digestable. Cat food has more salt in it than dog food, tastes better. Not real good for dogs to have. Kibbles keep their teeth stronger than canned food. Canned food is good if they are weak, small, or lactating.