I would go Creedmoor for the simple fact that has already been stated: less recoil means more practice, which means a more skilled youth hunter. The Creedmoor has enough knock-down power and then some for a whitetail.

I don't mean to dilute this thread anymore than it already has, but why not consider a .243? It has a ton of versatility, from deer, to coyotes, to groundhogs/squirrels...and its a pretty popular round so factory ammo should be readily available.