Which Is Better

[Jack]

Both are excellent, you can't lose choosing between those 2.
One small thing that might tip the balance: you'll find 270 ammo at every corner gas station. 280 ammo isn't scarce, but it isn't quite as widely distributed as 270 ammo. If you shoot strictly factory, that might be a small factor.
If you handload, pick the rifle you like in either caliber, and you'll be well equipped.