In my opinion, the "perfect survival rifle" is the one that works for you. It doesn't have to work for me, or for Aunt Tillie or Sergeant Bullwhip Psycho, USMC (a character from a comedy routine a cadet a class behind me at the Zoo used to do); it has to work for YOU.
I've written on the subject before. My own opinion is your rifle has to be able to work with minimal maintenance, under the field conditions you can expect to encounter where you are at any time of the year, and be chambered for a 'universal cartridge' wherever you are. Apart from that, trick it out however you like and carry as much ammo for it as you want or think necessary. As long as your rifle works for you and you can reliably hit what you point at with it, carry whatever you please.
Anyone who wants me to expound/expand on this, please contact me off-forum and I'll be happy to discuss this subject.