I'm not saying this is how your vet office is ran, but I will throw this thought out there. Every vet office I've been in is sponsored by a company; whether it be Hills, Eukanuba, or Purina. Since those particular clinics are sponsored by that company, they are required to carry and promote their foods as part of the sponsorship. That doesn't necessarily mean that that particular vet recommends that type of food over another, but in some cases, they are required to do so.

That having been said, of the "grocery store" foods, I would feed my pets Purina One over the other brands carried, but I still prefer to feed them their current diet (which shall remain unnamed in this thread, because that isn't the point) because I just have better results with their current food. This doesn't mean my food is better or that Purina is bad, it just means I have better results with this particular brand. And I even astounded the vet at their last visit because of all the Aussies she sees, mine have the best looking/feeling coats, clearest eyes, etc.

But just remember, no matter what anyone says -- feed what works for you and your pets! I encourage everyone to do their own research and find out what works best for you!