A G2 with a .22 LR barrel to get the kids started shooting, add a .22 center fire barrel when they're ready for that (.22 Hornet, .222 or .223 Remington, or .221 Fireball would all be good choices).
Since you handload, 7-30 Waters might be worth a look for their deer barrel when they're ready for that, not that .30-30 is a bad choice, either. And really, even a .357 Magnum barrel would work for a starter deer barrel. If your kids are good enough shots and it's legal where you are, you might even consider using the .223 barrel with Winchester 64 grain Power Points or a handload with 60 grain Nosler partitions (or some other factory or hand load with a good, bonded bullet) for their first deer barrel...