Mare Cimmerium
What Mare Cimmerium is
Mare Cimmerium is an albedo feature — a region named for how bright or dark it appears from a distance — on Mars, centred at 19.8° S, 140.0° E in the Aeolis quadrangle.
Where the name comes from
Cimmerians were ancient Thracian seafarers; "far western sea" (Homer). The International Astronomical Union approved the name in 1958.
What it would take to settle Mare Cimmerium
Mars scores 26.6 as a world. That number is the same for every square metre of it — but sunlight, water, radiation and the ground under your feet are not. This is the same question asked at 19.8° S, 140.0° E.
What this spot has going for it is sunlight — 95% of the sunlight the sunniest latitude on Mars gets. What works against it is water — outside the ice-bearing latitudes.
Computed from Mare Cimmerium's catalogued latitude, longitude and feature class — 74% of the model's weight had a basis here, and 2 axes were dropped as not applicable to Mars (radiation geometry, earth link). Gravity, pressure, delta-v and distance from the Sun are the same everywhere on Mars and are already counted in the world's own index, not again here.
What this cannot see: elevation. Slope, local shadowing and the polar “peaks of eternal light” — ridge tops near the poles of a barely tilted world that catch sun almost continuously while a crater floor kilometres away never does — need a terrain model this does not have. Where a real mission targets a pole, that is usually why.