Do you mean which dry food is healthy for dogs? Opinions will vary...the more hard-core of us will say 'none', and encourage a raw diet. But for those that choose to use dry foods, I would suggest that you look to one with whole proteins, zero grains, and as natural as possible...like Evo, Orijen, etc. These are not inexpensive, but quality does not come cheap.
Many dogs have food allergies and have trouble processing certain ingredients, which is why I'm a huge advocate of natural types of dog foods. Natural dog foods don't contain any artificial ingredients, preservatives or synthetic chemicals, which makes it easier for your dog to digest. Dog foods considered to be natural include brands, such as Blue Buffalo, Nature's Variety, Solid Gold, Wellness and Halo (just to name a few). Taking it a step further, there are many types of dry dog food that do not include ingredients such as corn, soy & wheat, since many dogs are allergic or have trouble digesting those ingredients. My dog (Dreyfuss) is allergic to those ingredients AND had dry skin, so I'm a huge fan of Solid Gold. He's been on this type of food for the past 4 years and he's uber healthy... Natural dog foods aren't very cheap, but they're well worth every penny in terms of keeping your dog healthy and happy.
I feed my dog with a rotation of grainless food like akklover too. He's kind of a picky eater, so I rotate with different food so he doesn't get bored. The only one he had problem with was EVO, I don't now if it's because of the high protein content or he ate something else bad and threw up, and he associated throwing up with the food so I had to give it (the food, not my dog of course) away. But he went through at least 2 large bags before doing this.