Why not have both? :) as far as "backup of human civilization" goes though, Mars has more potential: water, atmosphere (thin though it may be), higher gravity,

Why not have both? :) as far as "backup of human civilization" goes though, Mars has more potential: water, atmosphere (thin though it may be), higher gravity, and a day similar to earth. If the s ever htf on earth, a mars colony has a better chance of surviving one day without earth's help. I guess for me the question is if that will matter or we get strong AI first.