If I could have only 3 I would first pick a FN 5.7
That way when the UN soildiers come I can steal their ammo after they're dead.
Second, I would pick something in .380, probably walther. In a global battle it seems like a wise choice to have since the rest of the world is practically limited to .380
Third I would take a Draco or AR Pistol, as ammo would be easy to find in if **** ever hit the fan.
I know Glock lovers will say SW9VE is no good, but I like the way it feels in my hand better than a Glock 19, and it is smooth. The KAhr CW9 is a great gun for CCW. The S&W 442 is a simple revolver - will never fail you.