What is the best dog food?

I was at the pet store and a representative was there from a major dog food company. He was touting his company's dog food as better than the others because it was made from 50% meat. This is a dry kibble (or bagged) dog food. Dogs are after all, carnivores, so I tend to agree with him. When I go to the zoo, the tigers and lions are fed meat....not dry food. Doesn't the same apply to dogs?