My regular vet has different prescription Science Diet stuff. Not a lot of it, but some. He's never, ever pushed it on us and infact was happy to hear what we feed and he's also willing to talk to clients about Raw as well. He just doesn't sell quality brands.
The other vet I go to also has different prescription foods... some I think is Science Diet, but not all of it. I can't remember what the other kind is, but I don't think it's much better than Science Diet in the way of quality. I think he can have a tendency to push it on clients a bit, though he never has done it to me. But I do only see him when a dog of mine needs a surgery.