I think if I could only have one blade and I didn't know where I was going it would probably be a machete or something along the lines of one of those larger swamp rat/Busse knives.
However, I would also like to have a smaller fixed blade (between 3 and 5 inches) and my Leatherman Charge in addition to the large blade. Sometimes a small blade is just a better tool for the job than a monster chopper.
Nessmuk had the right idea. A large chopper (but I prefer a blade over an axe since it can do more), a mid-sized fixed blade, and a small detail knife.
