Nutro IMO isn't that great it's more of the middle of the road food. I personally wouldn't feed it.. I haven't heard of Proseries. It's up to you what you feel is best to feed but I'd stay away from Ol'Roy, kibbles n bits, alpo, etc. Purina and Pedigree isn't that bad, a lot of people feed it with no problems. Kirkland you can get at costco is fairly decent, Natural Balance is good as well. Blue Buffalo is good as well.

Just feed what is in your budget range and get something from your pet store not the grocery store.