The M14 is every bit as reliable as an AK. As a matter of fact, I'd say its MORE reliable for the fact that it has an exposed bolt which the AK does not. When the bolt gets excessivly fouled on an M14, all you do is drop the mag and cycle the action, the crap falls out the bottom. Worse case you can wipe out the muck from all around, over and under the bolt, even flush it out with water. Can't do that with an AK. You have to remove the dust cover and bolt carrier.
In a pure survival rifle, you will not be engaging the enemy in an offensive action. You will be using your rifle primarily for hunting, secondary as a defensive weapon, and then only to break contact to escape or for a scout/sniper role, in either case the M14 with better sights and more powerful round beats the AK hands down.