... parameters like
"do we keep it for infinity?"
"is film endlessly available in the format of our choice?"
"does weight matter, e.g. will we have a sherpa at our service as well?"
"will Eric H. be reachable in this hypothetical land, or will our chosen camera just continue to work forever?"
You know, stuff like that.
It matter what each person shoots, I'd say.... so you know, "it depends". But then my answer is usually: Pentax MX ... there are other choices I would make based on some of the above conditions, and there are other cameras that are my "favorite", but the MX is usually the one I'd keep.