Okafor is a budding elite NBA player.
His combination of agility, quickness, strength, and skillfulness on the offensive end is reminiscent of, Celticsblog favorite, DeMarcus Cousins; except, he's in the first year of his rookie contract and can be reasonably expected to acquire strength, skills, and the wrinkles to better utilize them in-game.
The answer isn't obvious today because of Okafor being a rookie and the CB lust for a defensive+rebounding Center, but this thread will be looked back on as an "Ibaka or Cousins?"-type thread even if Noel improves.
If the cost to acquire Okafor or Noel were equal, Jahlil is the player to acquire, easily.