10-22's are great, and you can accessorize the heck out of them,
but not my choice for a first rifle.
Bolt action magazine fed 22. I'm partial to the Savage rifles with
accu-trigger, but there are many fine candidates out there.
Pull the magazine and go single shot for initial training. Manual
action teaches them to make every shot count. It might
get pushed to the back of the safe by the 10-22 (maybe next
year?), but he will never outgrow it.