Agree on grain free kibble being problematic. I bought my dog a sample bag of a certain grain free food and he loved it. I purchased a bigger bag and only recently I realized that my dog's tumor grew during the period he was eating that food. I have pictures of him before and after he started that food and the tumor DOUBLED its size in a month. I don't think canned grain free food is any better, because there needs to be added something in the food to keep it fresh. Better to buy something that can be frozen instead of having an added ingredient to keep it fresh.
My dog now eats one of those subscription foods delivered to my doorstep. the reason why is because in the wild, dogs do not eat raw food. I know most people say raw food is great, but an Indian vet enlightened me by saying that dogs in the wild often eat road kill, and the dead animal was warm at a certain point.