The moon and Mars have their pros and cons. The moon is closer and has a shallower gravity well. I think Mars makes a better destination, though, mostly becau

The moon and Mars have their pros and cons. The moon is closer and has a shallower gravity well. I think Mars makes a better destination, though, mostly because of the atmosphere which provides CO2 practically for free. With CO2, water, and electricity, you can make methane. (Mars might also have easier to find water, but I don't know offhand what the current consensus is on that.) I don't know if there is any practical way of creating fuel on the moon. You could launch things from the moon without fuel just by using a big railgun or equivalent, but these things will presumably still need fuel to slow down at their destination.