What makes brand name cat food any better than store brand?

I know that some foods are full of unhealthy fillers like corn and grain, but aside from that, what makes one brand any better than the next? I do not want to pay more money just for a brand name if nutritionally it is no better than the store brand. I am considering feeding my cats raw, or a bare and raw food diet, but it looks very complex, and messy. Is there a dry food out there that is decent without being insanely over priced? I am looking at Royal Canin and Blue Buffalo right now.