I think the clear choice for survival situations is either an AK-47 or an AR-15 style rifle. Both are adequate for hunting, and both are reliable in rough field conditions (though the AK is significantly more durable than the AR). Obviously, both are excellent for personal protection. If you balk at owning a military style rifle, then my recommendation would be to purchase a pump action shotgun like the Mossberg 590 or the Remington 870, and purchase a combination of birdshot and slugs. You should have the bead sight on the shotgun replaced with a rifle-style V-notch or ghostring sight, for hunting and protective purposes.