I voted for clean water but after thinking about it some more,I'd like to suggest another "other" I might actually have voted for.

I think what I would miss most would be social order. I like living in a society where I am safe and I don't have to use violence to protect myself, my family or my property. As a civilized townie I don't know I would be able to become what I would have to in order to survive in a post-apocalyptic world.