Machete, hands down. A saw will wear out, a gun will run out of ammo eventually and it's hard to chop down trees for shelter with a gun and a multi-tool is just the kind of silly things people use when they can't afford real tools.
Also, I can sharpen my machete on the rocks when it wears dull.
It's pro for chopping down things, opening coconuts, and killing things that need killing.
Machete! Buy one now, get second one half off!