Nobody knows the exact nutritional requirements for Ball Pythons, so rats aren't necessarily better for Balls than mice. Many people will feed their Ball Pythons mice exclusively and their snakes will thrive, grow and breed.

However, rats have a larger range in size. If you're trying to add weight to a building female breeder or if you have a picky snake that eats periodically, you might be better off feeding rats which come larger than trying to feed multiple mice.