I love my 6.5 swede but for a grandchild or child of my own I would go 6.5 creedmoor everytime. It gives them the option of tons of widely available shelf ammo in stores all across America. Should the youngster decide not to reload they are not stuck in what could be a tight situation
I've told this story before, but it illustrates the challenge of being off the beaten path with a rifle chambered for a less common cartridge and no ammo for it.
A number of years ago I was hunting deer on the high plains near Wray, CO. A hunter from OH was staying a couple doors down from us at the motel we were staying in and had made the trip from Pomeroy, OH, without any ammo. He called every gun shop that he could find a telephone number for in western NE and eastern CO, but couldn't find any 6.5x55 ammo east of Denver. I loaned him my spare rifle, a S&W C in 30-06, so he was able to go hunting on opening morning and punch his tag. If he'd had a rifle chambered for a more common cartridge, he might have found ammo and been able to hunt with his own rifle.
