@judyperalta If you can get over the fear of Purina, the Sensitive Skin and Stomach line is corn/wheat/soy free.
I personally used to be a hardcore boutique food feeder for like 15 years. Probably the only thing that saved my dogs was the fact that I rotated/changed food constantly and when we first started feeding "grain free", it was before legumes overtook the formulas. I worked in pet retail and sold/believed in all the "natural" foods. I still wish I could trust them, but having spent some time going down the nutritional DCM rabbit hole and years of reading personal stories from people whose dogs were affected and some happily recovered after switching to the so-called "garbage" brands, I can no longer comfortably recommend or feed those foods. Frankly I'm grateful I no longer work in pet retail and have to wrestle with that moral dilemma.
It infuriates me that the boutique brands refuse to take it serious or put their money where their mouth is and PROVE their foods are safe. That's all we're asking for -- proof. Not slick marketing or empty assurances or hopeful theories about "the problem is taurine and our food is full of meat!" etc. Diets containing grains also have been associated with nutritional DCM just from being poorly formulated. For example, one of the reasons why taurine gets added to all cat food is because they learned the hard way back in the 80s that certain Lamb & Rice formulas were causing DCM due to taurine deficiency in cats and some dogs. Lamb is a naturally low-taurine meat. So while we know that can be a factor, it's not the ONLY factor. A poorly formulated diet or a diet that doesn't provide the nutrients as-fed vs on-paper can still cause problems.
I personally feed my dogs Royal Canin because they've done really well on it and I trust their quality control processes and of course they do a ton of research and testing. Most of their retail diets contain corn or wheat. There is nothing inherently bad about those ingredients unless your dog is allergic. Boutique companies like to say they're "filler" but my dogs have the smallest, least frequent poops on RC with all their so-called "fillers" than any "meat filled" boutique brand I've ever fed (short of straight raw food). If you read the research, wheat gluten and corn gluten is actually more fully digested and absorbed by dogs when prepared properly in dry diets than even chicken meal. And the chicken by-product meal that RC purchases is specifically rich in organ meat, which is highly nutritious. They also have grain-free prescription diets that are tested and safe if a dog has a legit grain allergy. Each animal I have is on the formula that works best for them. Every animal I've owned has thrived on RC, and I'm amazed at how consistently it feeds, looks, smells, performs etc. The drawback is that it's a little on the pricey side, particularly the prescription diets, but not any worse than something like Carna4.
One thing I will always say, and this was true even when I sold boutique foods with my whole heart believing in them, is that there is no such thing as "the best food". It really just depends on your dog's needs and your personal needs. Every food that one dog thrives on is another dog's worst nightmare.
If you are REALLY stuck on no "big name" brands, FirstMate does sell a grain-friendly line that is affordable and does not contain any legumes or potatoes. Their foods are not formulated by a veterinary nutritionist however and they do not do feeding trials.