I have had very healthy and long living dogs with Purina dog chow...Admittedly only on it for 2 months.
Lol, it would take longer than that for problems to show up if you fed them only cardboard and old shoes.
Our dog eats a 50/50 mix of premium dog food and our home blend of cooked venison and rice. We made all of our dogs' food, using supplements, for several decades; I think it worked out pretty well, as our MastiffXDane lived to almost 14 and our PitbullXPyrenees was still going for multi-kilometer daily walks with me to within a couple weeks of her eventual passing at 17. Those are healthy ages for any dog, and amazing ones for such large dogs. But our current vet has convinced us that simply using an admixture of quality commercial food with our home brew is a more economical and more effective means of providing all vitamins and trace elements; it's been a couple years now...not months!
...and so far so good.
I read a lot of dog food labels before settling on one; would have been even pickier if it was going to be the dog's entire diet. I have a neighbour who feeds her little mutt Farmer's Dog, and I was impressed when I saw and smelled it; pretty sure the ingredient list looked good, but I never seriously considered it because of the cost.
I like the idea of a brand which is easily and locally available. I always have a couple big bags on hand, rotating them out for freshness, so that if something comes up that interrupts the supply I will have a couple months' worth on hand to give me a chance to find a substitute and switch the dog over graduallly.