I'd see whether or not he's going to play multiplayer. If he is, then see if his friends are using a PC or console. This is because most games don't cross play with different platforms. So if his friends are on a PC, get a PC. On a XBOX? Get a XBOX. PS4? Buy a PS4. That is the smartest choice. Though a good enough gaming PC tends to be a little more expensive then the average XBOX or PS4. And considering he's ten, I'd say a console is better, since he probably won't need to use all the features of a PC since all he's doing is gaming. Good luck on your search!