i tried to post this last week after watching The Candidate but my account was locked probably to protect spoilers.. but now that I can get my word in I wanted to express that I believe strongly that the issue of whether Jin or Sun was the Kwon Candidate has been resolved in that episode for good reasons:
-Jin and Sun were touched by Jacob at the same time on their wedding day, and right AFTER they were married symbolizing ONE whole; and
-they died TOGETHER. neither of them could die before separately, as Jin survived the boat explosion. I think they were either meant to live together or die together because their existence as a whole had been one candidate to protect the island together. Only by dying together (and not at the direct hands of the MiB), they were eliminated as a possible candidate to replace Jacob.
I really dont believe that we were led to believe that one Kwon was candidate and not the other, especially when both were touched by Jacob and brought to the island together. and im sure this Kwon storyline is officially over for the show so its left to us to determine what we believe, but I feel the show strongly led us to them being ONE candidate.