The most viable places on Callisto

Elevation. Every score above comes from a latitude, a longitude and a feature class — never from a terrain model — so slope, local shadowing and the polar peaks of eternal light are invisible to it. That last one matters: on a world tilted barely a degree, a ridge top near the pole can catch sunlight almost continuously while a crater floor a few kilometres away has not seen the Sun in two billion years. This model scores the average surface at a latitude, so it reads poles as dark and ranks them accordingly. Where a real mission targets a pole, that is usually the reason — and the reason to read this as one input, not a verdict.