You didn't mention how old your son is. Corns are very good starter snakes, especially for younger children. They rarely bite and can tolerate a lot of handling. They aren't as sensitive to envirnomental changes as Balls, and are great eaters. However, they require a very secure cage as they are notorious escape artists.

There really is no right or wrong snake. They both make excellent pets, however I would probably recommend a corn snake if your son is under 10.