I'm sure there are valid studies showing complete diets lead to longer, healthier lives, and I can tell you from my personal professional experience that is what I've seen.
The next question is "What is a quality food?" My point is don't believe the advertising hype saying that one food is obviously better because is has XXX ingredient or doesn't have YYY ingredient. Also, don't rely on your google search or website advisors as the final authority. The websites often have an axe to grind, preconceived perceptions or opinions or gain advertising $$ from something they promote.
If you want really good information, talk to a veterinary nutritionist, your veterinarian, your friends who have had good experiences with ... food.
I seldom recommend one food or one brand. I've found the best quality food is the one your dog/cat will eat, have normal BMs, and are healthy when eating it. That isn't the same food for every animal.