Don't be fooled by claims on the bag of "all natural" or "organic". You need to look at the ingredient listing. When I'm looking at a dog food, I look for no corn (in any form), no by-products, no unspecified protein sources (meat meal vs chicken meal), no wheat and for me, no barley because I have a dog who does not tolerate barley. I also don't like to see tomato pumace or beet pulp which are both stool hardners and can mask problems - but I will tolerate those if the rest of the ingredients are good. I also avoid any food that lists a grain as the first ingredient.
IMO, Wellness produces a better product than Nutro.
Also, a dog will eat more of a poor quality food trying to get the nutrients that it needs so you end up feeding more, and the excess comes out the other end of course. The benefits of a good diet (whether that be kibble, raw or homemade) is that you'll feed less and have less waste to clean up and of course your pet will be healthier.
I have people comment all the time that the newfs must cost a fortune to feed or that their poops must be the size of a chihuahua. The newfs on average eat less than 3 cups a day of food, and their poops look like they came from a dog less than half their size.