If you choose an Enfield, I would stick with .303. I have had problems with the #7 that I have. I did get the ejection problems almost fixed, but not enough that I want to trust it with my life.
But suprisingly, the #7 doesn't kick that hard. I shot mine from the bench last time until I ran out of ammo, and I still wasn't sore. In fairness, the reliability thing is most likely just a screw, but I just don't feel like messing with it anymore.
But, I am getting the sense that they guy who started this thread wants something non-PC. In view of that, I would suggest something that has as many evil features as you can afford.
Ammo for the eastern bloc calibers might be more difficult to get in a pinch, but it is also only $80 for 1K of 7.62x39mm shipped to your door. For that, you could squirrel away a pretty good supply relatively cheaply.
If something big did happen, any ammo for any caliber would probably be sold out, so the resupply would be a moot point. And anything that happens will only last for a few weeks or so before the authorities get things under control. The up close sting of the AK is a very good advantage.
Like I said, a bolt action 308 would be my choice, but that doesn't mean that I would want the guy with the AK shooting at me. Even with my more powerful, accurate, scoped rifle, it would make me nervous.
I would avoid the 5.45mm. It isn't as common as the 7.62x39, 7.62x51, or the 5.56, so it may be hard to stock the same amount of ammo as easily.
That, and for long term, I think that the other rounds will be around longer. Something to consider if you plan on shooting it for many years.
So, if I felt the need for a non-PC rifle, I would start with the AK.
In fact, I did.