I would be grabbing my HK 91. I'm a big guy, I have access to land out in the boonies, and I'm sort of "prepared" in some ways (well, I also have things stashed for different reasons, not like prep nut stashed, but kind of like a "case study" of sorts..)
Anyway, why the big damn gun? Because I can carrry 150 rounds of 308 in the distances I would need to travel and be fine. Plus, the HK91's design (roller delayed blowback) is such it's made for significant abuse (no gas system to worry about getting munged up) and is like a higher powered AK-47. I can configure it in different ways (long range, short range, night vision) with the claw mount system and keep a zero pretty well with the different scopes. I can even make it fully auto with just a few minutes with a saw (it's legal to own all the materials, just don't do it until SHTf). 308 will put down most animals and all men. Find me a guy who can handle a 308 to the chest and I'll stay the hell away from him lol.
About the only draw back with an HK91 is the way it tears the hell out of brass. But, If SHTF, who would have time to reload anyway? At least not in the immediate future. Would be too busy killing "zombies".
I would definitely have a .300 blackout rifle stashed somewhere with a suppressor. If someone did happen upon my little area, would rather pick them off without giving away my position as easily.
I would have a .22 stashed somewhere, as well a revolver or three. .357 hands down, 38 special and .357 are fairly common. My .22 of choice? American 180. Swarm of angry bees...
Lastly, I would be fine in my little area...as long as no one comes trying to put the f*%k to me, I wouldn't be out bothering a soul...