Everyone like different things. It depends on what he wants and his type of game he plays. Ask him. If not go to one of the local lax stores and tell them what you are looking for. They are very knowledgeable. I would not go by what people say here. It is a very personal choice.
Agree 100%, but you can't ask the kid and ruin the surprise. Maybe you can "borrow" the stick he has now and bring it to the shop and show it to the sales guys. But it is different for every player. I've heard an MLL defender at a clinic say to the kids he just plays with whatever they give him, while another is very specific on the shaft, head and stringing. Funny but true.