They would be 5 I already have.

1. Oly PCR-5 w/M-16 stock, red dot, vertical foregrip,  and Surefire
2. 870 with Knoxx Copstock and Surefire fore end
3. Taurus PT92
4. Kahr P9
5. Kel-tec P-32

Although long arms are far more effective, most of the time we are stuck packing pistols, so I want a lot of flexability in my side arm choices.

SHTF or some sort of revolution

(same mags, ammo, and parts)

I'd be looking for versatility

1) AR15 lower, with various uppers, including a .22 upper, a 16" upper, a 24" heavy barrel upper... probably more
2) 1911, kimber most likely, with a .22 conversion kit, a carbine upper.... Actually maybe a new Dan Wesson, as I hear rumors that the Dave Pruitt model will be capable of caliber conversions to 9mm, 10mm, etc.
3) Remington 870, with stocks, barrels, chokes, mag tubes, etc. to do just about anything you'd want to do with a shotgun.  Take the family home defense gun & change the barrel & mag tube and go out bird hunting.

Those three pretty much cover 99% of what I'd need.  That leaves me with 2 huh.....
4) I might have to go AR10 in this case, since I could again have several uppers.
5) Kel Tec P3At or .32 for CCW and backup.

The best weapon in that case is a .22 rifle or pistol.  Quietly take out a member of the opposition, and co-opt their weapons and ammo.  Then replacements, ammunition, accessories are all easily attainable.
Watch "Red Dawn".  Those kids start out with hunting rifles, and wind up with AKs.

My list:

SIG P226 9MM

KELTEC P2000 or other SMG/carbine that takes SIG P266’s mags

MIA

Bushmaster AR15 with multiple uppers

Mossberg 500 12 gauge

Ditto

Well since this is completely hypothetical, I'll be hypothetically using someone ELSE'S money.

[nana]

No pre-bans or NFA what are you running for President of the NRA or something?