If one of these 2 survived, it has to be Jin.

How could Michael have survived when we saw the boat explode right after Christian said "You can leave now Michael" ? Michael has been trying to kill himself for a while now, but the island wouldn't let him. This proves to me that after helping the others leave the boat in time, the island thought Michael's work is finally done and that he can go in peace.

Jin COULD have jumped from the boat, but we surely didn't see him do so, and neither did the people on the helicopter.

And seriously, with the amount of C4 that was on the bomb, if any of these 2 survived.... heh