I'll be crossing this bridge in the near future myself. My son is five and I'm going g to put a rifle together for him soon.
I've got a 700VLS in 243AI. I think I'm going to cut it down and put it in a more youth friendly stock or chassis that he can grow into. Obviously I'm already set for components and equipment to load the AI, but if I wasn't, I think I'd do a 6creed. And I still might. I love the originals but there's no doubt, the new class of cartridges in the creed and prc families are here to stay and I like the fact that the 6creed can shoot the light 70gr class of bullets up to the 110's. I'm only recently a fan of the 6mm but after playing with this 243AI I'm hooked.
I started out with a 300winmag and I don't recommend that lol. After that I shot a 22-250 for years and pretty much shot all se Texas had to offer with a 55gr core-lokt. I actually did less tracking with the 250 than the winmag. Come to think of it, I never tracked anything I shot with the 250, every deer was drt. I always popped the high shoulder though.
My brother killed his first deer, a fair size doe, with a 223 shooting federal premium 55gr sierra HPBT gamekings. She went about 20 yards and piled up. Boiler room shot, got both lungs.
When I got married, my wife had never hunted or shot anything ever. I started her with a remington model 7 in 7-08. I'm a huge fan of that rifle/cartridge combo. Shooting the factory hotnady reduced 120gr sst loads it's a potent, handy combo.
Just some of my own experiences over the years.