Navy/Air force if he wants to do technical stuff. Make sure that what ever deal he makes with the enlister he gets it in writing.
There are technical MOS offering in every branch. Having played the system I recommend finding a reserve unit with an opening in a desired occupational specialty, and then moving to where it is to join that unit.
When he is sent to boot camp and MOS training, he needs to keep his nose to the grindstone and claw his way to the upper levels in class standing (which won't matter to most people in training but which will for him).
After training, he can put in for active duty if his class standing is good, and if it is really good he may leverage it into a good duty station.
USMC 2884/USAF 30451/USMC 2171