- Mars has an Earth-normal day/night cycle for growing plants. The day is about 24 hours and 40 minutes. The moons is 28 days. That doesn’t work for growing crops, at least not under natural light.
- Mars regolith has all of the nutrients you need to grow crops. It has nitrogen, potassium and phosphorous in the regolith plus all of the required micronutrients. We would have to add bacteria, including the ones that consume perchlorates but we could definitely grow our own food in a greenhouse there. My guess is it once had life and that is why all of the nutrients are there.
- Mars has more water ice than we could ever need. If we terraform it someday there will be vast oceans from the ice that is there. That also means oxygen. The moon lacks both. though it does have some water ice at the south pole, though a tiny fraction of what is on Mars.
- Mars has more than double the gravity of the moon. I am not sure how much is needed to be OK for humans, I think Mars might be enough with a little bit of hard work added but we actually have no data on that so that is only an educated guess.
- Mars has about 1/4th the radiation due to a thin but real atmosphere. That ratio goes way up for solar flares due to Mars being farther from the sun. It is enough that survival on the surface is practical, though colonists will probably bury their habitat under about 1.3 meters of regolith just to be sure.
- Mars is farther removed in case of a catastrophe on Earth. That means a much higher chance that the species and consciousness survives if the worst should occur. It appears intelligent life and self-awareness is a pretty rare thing. In 50 years of SETI we haven’t found anyone out there. Consciousness is precious.
- Mars can be terraformed some day. Not now, but it actually has enough gravity to hold an atmosphere if we eventually give it an artificial magnetic field.
Mars is so much more survivable than the moon. It isn’t even close.