"Once an infrastructure is constructed it would be better on Mars, and here is why.
First, in terms of energy it is easier to get to and land on Mars because the martian atmosphere assists in slowing any vehicle trying to land on it. That more than compensates for the additional original velocity needed to get to the vicinity of Mars versus the moon.
Second, Mars is much further out from the sun, and it is much easier to get to the outer planets from there (the velocity changes required are much smaller). Or, to put it another way, Mars is further up the gravitational hill created by the gravity of the sun.
Third, because Mars has water, rocket fuel (hydrogen and oxygen) could be manufactured on-site. Water ice is theorized to be present at the poles of the moon, but none has been demonstrated thus far.
And, last, the equatorial speed of rotation of Mars is about 880 km/hr, which would add that much velocity to a rocket launched from there. The equatorial speed of the rotation of the moon is less than 16 km/hr, adding virtually nothing to the velocity of a launched space vessel."
