Dog food is one of the hot topics in FB groups I'm in. We always want the best for our furbabies. You may have seen the news about grain-free dog foods that contain certain ingredients that may be linked to heart disease. I would not put a dog on grain-free unless there was a medical reason to do so. You also want to be aware that all dogs foods do not have the same calorie count. If your dog is not very active, they are going to need less calories than a dog that is doing agility training every day or something like that, for example. Here are some brands that vets recommend: Purina, Hills and Royal Canin.
Here is link with some questions and answers about grain-free:
Grain-Free Dog Food Q & A's | CVCA Cardiac Care for Pets
Here is a link from the FDA with questions and answers:
Questions & Answers: FDA Center for Veterinary Medicine’s Investigation into a Possible Connection Between Diet and Canine Heart Disease | FDA