I agree that the Primitive Natural is the best. However, I think it has a high ash percentage, but don't know that for sure.It's a good company and some of their foods are quite good - Primitive Natural probably being the best. Some of the other formulas do seem to be, as Zookeep mentioned, a bit heavy in legume ingredients and light in meat.
Yes, it is the best variety of Earthborn. It does have 12 percent ash, which is very high. Maybe someone will weigh in on whether they think that high of an ash percentage is a problem.