If I was buying one of each - handgun, shotgun and rifle, I'd go with: 9mm, 12 ga, and 30-06 hands down. Some might disagree with me on the 9mm, but its NATO and the most widely available pistol round the world over, high capacity mags are also a plus. I'd buy Hydra-Shok JHPs btw. You can't beat a shotgun loaded with number 4 buckshot for home defense IMHO.