All kibble includes something, used as a binder, that dogs aren't equipped to process...Grains in some foods, potatoes, peas, etc in Grain-Free foods. There is nothing inherently better about Grain-Free unless your dog has an allergy or sensitivity to grains.
If your pup does well on the food and is growing at a steady rate then stick with what works. Personally, I like to make sure that Calcium and Phosphorus levels are appropriate for a large breed puppy, and that the food is AAFCO certified as an All Life Stages food. As long as those 2 boxes are checked, the food is from a company I trust, and my dog does well on the food, I'm happy to feed it to a puppy of any age.
Omen v Wolfstraum
Jasmine Katie v Doolanshaus