Choosing the right place on Mars for a settlement would be of course an important decision because once it's there it would take much time and money to move on to another, better location.
Because the availability of water and energy are among the most important factors that would determine such a choice, can it be estimated at what depth boring for water near the equator, together with the availibility of more energy there, would become more economical than mining it near the surface at the midlatitudes ?
NASA's Treasure Map for Water Ice on Mars shows us the image above with underground water ice on Mars at varying depth at about 40⁰ latitude and higher.
However, some parts of Mojave crater near the equator display a high concentration of closely spaced pits. It is believed that they form from steam produced when the heat from the impact process interacts with ice in the ground.
So if we assume that the groundwater ice is still there, at what depth would it become more economical to bore for that ice than to mine for it at 40⁰ latitude, regarding that near the equator it's much warmer and more solar energy is available ?