I'm thinking a .30-06 would be a good rifle to have, along with a 20 ga. shotgun for home defense.
.308 (make sure the rifle you buy is compatible with higher pressure, slightly different sized military 7.62 x 51 ammunition) and 12 gauge are MUCH more practical from a logistics and price point of view, both being used by various military and law enforcement agencies around the world, and thus, much more available and cheaper to purchase.