something small and something large. On the belt, a 3 or 4. Strapped to the pack, a Junglas or Lite Machete, depending on the environment.
I own the 4, 5, Junglas, Lite Machete, and HEST. The 5 is bad ass, but heavy, and has the thickest edge of them all. Again for escaping downed aircraft.
For camping, the 4, hunting the 3. Chopping wood, clearing trails, killing a boar, the Junglas. It's 9.5" of blade, light weight, and fast. If you need more reach, the LM is a great machete.