I've probably read all those things about SHTF guns and ammo on forums, heck I'm probably the progenitor of some of it. In all seriousness, the AR and AK are fine for the SHTF. The AR is accurate and light, the AK is reliable and for medium ranges the x39 is a great cartridge.
Back in the 80s and early 90s the Mini 14 was a decent choice because the AR's weren't "all that" back then. Times changed, the AR got better, the Mini didn't improve much and is obsolete in comparison. If the Mini was $300, I could see it being good for budget use, but even then, a budget AR is about $480 and worth spending more for.
The G3 and FAL are Cold War antiques. Even if you wanted .308 in a semi auto, an AR10 is better and as time goes by the AR10's popularity will only continue to increase while G3's and FAL's will be forgotten.
About any bolt action works fine. I'd just stay away from Remington. Savage and Ruger are killing it with the budget stuff while CZ can make bolt guns that will never die, look great, and shoot great.
As for the pistol calibers, any fanboy can make any argument they want, but 9 and .40 are at the top for SHTF, .45 is in third place. .45 is heavy, lower capacity, larger pistol, more expensive ammo. I don't care about the felt recoil argument of .40 and .45, you can learn to shoot .40, it's not impossible. .357 Sig has no business existing until a military branch adopts it and factory ammo prices drop as a result. I was hoping the new Sig pistol would be adopted in .357 Sig, but the entire military has a stick up its ass for 9mm Nato.
Revolvers for SHTF aren't the best, but they can work. If you have a sub 30oz revolver, then you're not weighing yourself down and a .357 has a lot of power. .44 Mag is for hunting, guns are heavy, ammo expensive.
The best caliber for SHTF is .22 LR. Buy thousands of rounds of the CCI Velocitor and Standard Velocity ammo, use the former for power in a self defense situation, the latter for quiet small game hunting. Now, that's not to say .223, 7.62x39, 9mm, etc. are bad, they just don't have the advantages that .22 gives namely ease of shooting, light weight, cheap.