I think I know one way to answer this with more than one answer.

If I could know the situation I would choose the knife to suit it.

Urban: SS4 or my Bad Warden as alternate. Concealability

Suburban: Guard or Hook as alternate. Versitility

Rural or wilderness: Dog Father or FSH, it's good to have a chopper. If I need something small I'll just Knap it from local materials.

If I don't get to know the situation, I'll take as many as I can get away with... <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

There's saying that I really like when this type of question is posed:

If you can take nothing, take a knife, if you can take only one thing, take another knife... <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />