I haven't watched Attack on Titan in a while so I'll skip that.
1. Where would I feel safest - definitely Godzilla. For all his destructive capabilities, Godzilla isn't really malevolent or intent on harming humans. He defends himself and kills as necessary or sometimes ends up killing just through indifference.
2. Which is most fun - zombie apocalypse. Especially TWD, since these aren't fast zombies. I'll probably die anyway but I might get the chance to shoot some zombies (can't really say I'd have any success shooting Godzilla or Kaiju). There's also a dark appeal to living in a apocalyptic world where societal strictures no longer apply. Godzilla and Pacific Rim are not exactly apocalyptic worlds yet. They're at war but you don't have the same fall of government that a zombie apocalypse has.
3. Highest chance of survival - still Godzilla world. As mentioned, Godzilla isn't really intent on harming humans, plus he's only 1 monster which the military can keep occupied for quite a while. 2nd survivability would be zombie apocalypse, because at least zombies can be taken down by normal means. A full blown Kaiju invasion is not something humanity will survive.