If I had to narrow it down to just one I would pick the DM or Scrapper 6 for urban, FBM for Africa and DF for the American wilderness.

The FBM because in Kenya we don't really chop for our firewood as we just use 3 logs and push them close for a large flame and pull them out to lower it. So I can have my chopper but not really need to chop logs.

The DF is tip heavy so if I am supposed to choose one blade (not even an axe) then the DF is the perfect choice for chopping.