I have always fed mine Science Diet & they are very healthy.

Science Diet gets a mixed review here on PT. One of the objections is usually that it contains corn, which can't be digested whole, but my vet (who used to work near their plant) told me that it is so finely ground, it is not a problem. She felt its actually a very good kibble. You'll here other objections here too.

Science Diet also produces lines of specialty formulas often prescribed by vets for different problems.