Tell GR: Zombies or Aliens?

When it comes down to it, gamers love killing loads and loads of things. Seriously. There's always a ton of killing in games. Some games even make killing out to be some sort of high-score contest, with Horde Modes, Firefights, and Zombies. If you had to choose one thing to kill from now until the end of time... or at least until you died and your score stopped rising, would it be interterestials or all the dead people rising up from the grave?

Would you rather shoot zombies or aliens?