Great topic.
I looked back at the title and it contained the word "perfect", wow, I think we have established there is no "perfect" , but there are some good choices.
The M6, mentioned above was purpose built with the intent on survival, good choice.
I like Runningboar talking about his home state, it brings to light exactly where he is most likely to be in a survival situation, and also what he may face (feral pigs vs. grizzly bear).
I see breaking this topic down into some distinct sub-sets:
Long Term or Short Term? LT , ST
Wilderness or Social/Urban Disaster W or UD (Urban disaster)
Urban disaster is also referred to as when the
STUFF hits the fan (SHTF)
Whatever the Survival situation, it calls for dealing with what you actually have on hand, and the situation itself. I travelled across the entire US one summer, camping and visiting many national parks. I could only take one firearm (and keep it well hidden while in the US parks). I chose my trusty Ruger 77/22 bolt action and a brick of Winchester T-22. The weakest link was the Optics (scope). Yes, scopes are durable, but drop it on a rock, and it can become worthless. The .22LR wouldn't have done a lot about an angry Grizzly bear, but, it's better than nothing.
In an Urban SHTF/ get outta dodge/ protect your life type of situation the first 24 to 72 hours is critical. That is when you will meet up with anything from gangs, or even hillbilly desparados blocking the country roadways, even right up to a bear you find at your temporary camp the 1st or 2nd night out. After making sure you have Water and Shelter, then your mind will turn to food gathering.
For the SHTF situation, I see myself always grabbing my AR15 and as much 5.56 as I can carry. In North America, defending yourself against another human (a bad guy) is the most serious siuation you will ever encounter, short of a Grizzly or Polar Bear attack. And even in the wilds, you will run up against more humans, than Bears. I've run across people in the dammdest of places, where you think you are 10 miles from the next living thing, and there they are, squatting by a little smoke belching campfire, or hiking the next ridge over. With 6 billion of us, Humans are the cockroaches of the earth.
I do like the .22LR and the 20 or 12 ga. shotgun, don't get me wrong.
But I find myself grabbing for the semi-auto .223. and partly because it's what I know the best.
I fire my sidexside 12 ga. at the range once in a while, but, I'm not confident enough with it take down prey and predators, although it's pretty intimidating when it comes to other humans looking down those twinpipes.
My 30.06 weighs about 11 lbs, too heavy, too powerful, you aren't taking down a rabbit or squirrel and finding more than a foot or 1-inch peice of fur left.
My Ruger 10/22 is set up as a silhouette gun, scoped with heavy barrel, would still work, but the optics bother me, a lot. The scope gets damaged, and you are screwed, blued and tattoed. A standard Ruger 10/22 is near the top of my list.
For all around Long Term survival, go with iron sights, lightweight, and a caliber that is readily available. You would be able to trade food or water for some .22LR ammo, as it will be fairly universal. Trying to find someone who has .379 Weatherby Magnum or dry FFG powder may be another story.
If you run across an abandoned house, what is the most likely round you will find in the closet or on a shelf? .22LR