Please help me with cat food!?

My family and I are getting 2 new kittens soon (6 weeks old, getting them in 3-4 weeks. One boy, one girl) They are staying at a foster family until we can take them because they were found abandoned in the wild. (In woods in a town, but without a mother or father) Right now, they are being fed Kitten Chow and/or Purina kitten food. What would be the best and healthiest wet and dry food for cats? Not kittens, I'm talking after 6 months. When I say healthiest I mean with the least amount of chemicals, all natural ingredients, healthy, good amount of water or fluid (for wet food) ? Answers are greatly appreciated ! Thank you!