Sure, I'll play too...

This one is making the rounds:
One Handgun, One Rifle, One Shotgun. You are able to choose just one of each for self defense with NO modifications.

Presuming this is in the "SHTF" vein...

GI 1911A1, Mini-14/30, 870x12ga.

1911 should be pretty clear. 8+1, big round, and at GI specs, it's a damn reliable pistol. Detail strip can be accomplished with a minimum of tools, ball ammo is both effective and easy to handload. Plenty accurate to 25yd and beyond with a bit of practice.

Mini-14/30. Why not an AR? Because while an AR is much more accurate rifle, it's also much harder to maintain. A Mini will turn in 3-4MOA without trouble using the factory ring sights, and in my experience, will feed anything you can fit in the magazine. Brass, steel, whatever. Don't count on finding your brass easily, though.

870 (or 887) 12ga. Ditch the 26- or 28-inch bird barrel and put on a 18.5-inch cylinder bore with dual beads. It'll shoot foster slugs beautifully to 50-75yd, and any kind of shot load will work fine. No gas system to maintain, and most 870s will run on minimal maintenance of any kind.