I voted for "Nuclear/Asteroid Fallout (e.g. Fallout or Lucifer's Hammer) " though the 2 possibilities mentioned in it are quite different.
I think that "asteroid fallout" has the potential to unite humankind, but that "nuclear fallout" would only further divide us.
Cheers, Rob
Comment on Re: My preferred post-apocalyptic world to live in if I had to choose one: