Russian sks with laminated stock.
The way I am about a nice little UZI or STEN.
Marlin take-down lever action .22 LR. They will run forever and kill most anything with a head shot.
Might be cap and ball revolver here pretty soon.
Me? Hell, I have (well, had before the boating accident), the M1 Carbine, the AK and the 10/22 for short work. Many rifles in heavier calibers for the longer range stuff. I also have my handguns (.45 and, yes, even 9mm) for the close quarters work.
If i understood the OP correctly, the question here is what is the perfect rifle, singular. You have only one rifle for all SHTF purposes, not a safe full for various purposes. Sorta like asking a pro Golfer to leave his golf bag at home and play the course with one club versus asking him which clubs he brought in his bag today.
1 gun only? 22 lr
to be all prepared, you need say 5-6 guns..
one of the 357 lever actions would be a good rifle. could handle the 38/357...
30-30 is probably the second most popular hi-power rifle cartridge (after 30-06). In my neck of the woods, everyone has a 30-30.
ak is just for hi-cap purpose.....decent range, good knock down.
gotta think of what ammo you will be able to scrounge..