I would say a laptop is the best option for him since he will be using it for school. I have thought tablet is good choice, but it is not as useful as a laptop because laptop has the keyboard in which it is easier for him to type out things. Tablet is convenient but also not the best way to use for school work.
I would get them a laptop as it has all round advantages and to me a tab seems to be more of a social tool than something that would aid a student in getting results. I think that you would also find that your son would appreciate the laptop more and progress in their education more with the laptop
