Let's go extreme:
   Everybody dies except for two situations:

   20 year olds only Earth.
   2 months old only Earth.

   I'd choose the 2 months old only Earth. There'd be more death?
   Likely. Would some survive? Likely. What would come out of it?
   No idea. *That's* what makes it more valuable to me.

   With the 20 years old only Earth, it's pretty predictable what
   would happen. Variations of what we already know.

   Mind you, I wouldn't exist. I would never find out. I'd be dead.
   That's ok. I'd still choose it, were it my last push of a
   button.