Eh... naturally, I have to say go for the 7mm08 as it's my favorite caliber, but either will do the job. As said, the 7mm08 has better ballistics and more power than the 243. The recoil (atleast in my rifle, a model 7) is almost inconcievable. Brings a smile to my face every time I shoot it, knowing I've got that much power and no recoil. My personal 7mm08 is a great shooter.

The 243 will be more simple because of only having one kind of ammo. What rifle is your current 243 in? I suggest looking at the Remington model 7's for your new one (regular or youth model, depending on the kid)

JMO
Timba