The healthiest dog foods would be dog foods that contain grain which is good for the dogs heart.
Also any organic based dog food is much better for the dog than non organic dog foods and it's a good idea to feed the dog some rice, vegetables and even some chicken.
Purina beneful and Blue Buffalo dog foods are good healthy dog foods that both my dogs have enjoyed and they are considered to be healthy for them as well.
Some other healthy dog foods for dogs are Ollie's Healthy Turkey Fare, Taste of the Wild dog food and Pet Plate Chompin Chicken dog food.
It's sometimes worth spending a bit more money on the dog food that is healthier for your dogs but if not as long as you're feeding the dogs then they'll be fine.