Future Moon Base Sited! the key points:
Shackleton crater (best image)
a resource of hydrogen, likely in the form of water ice, ammonia, and other materials
at the Moon’s south pole and is some 30 kilometers in size
peak of external light - more or less continual Sun. solar energy becomes usable all the time. in the permanently shadowed areas in that region, various astronomical instruments could be operated with telescopic optics kept cold and stable
I posted this on MetaFilter and got some discussion.