I finally picked double-jump over 'breathe underwater', but it only won by the tiniest amount. Maily cause, with double jump, you would never need a parachute (providing it works like in some video games, where the sudden change in velocity doesn't cause you immense pain), as you would be able to fall to within a foot of the ground, jump, and land as though you only jumped regularly ... plus one foot.
Also, jumping off a building to fly-kick someone in the face then suddenly changing direction and not hitting them would be awesomely-freaky.
Also, fences would no longer be my enemy, and I can run away from any 'Cole McGrath' type opponents with ease, as putting a chainlink fence between me and him/her would make me invincible.