I think Kevin deserves it the most. He played the game under the radar, which I said was a great strategy about 2 months ago. He was kind of staying out of the controversy and not getting himself in many fights.
He played his cards at the right time and maybe it was his strategy all along to appear weaker and not win much until later on in the season. This makes sense considering he wouldn't take Lydia off the block b/c he didn't want to make the HOH mad and stir up trouble for himself.
The other 2 just rode on people's coattails. Natalie rode on Jessie's ass. Jordan rode Jeff's ass, didn't win anything(w/o Jeff's help), and was really clueless when it game to how to play the game. But she made it this far, so really, despite not having a strategy, she got this far. It has more to do with the perception of her as a non-threat than anything else.
You could even tell that no one was gunning for Jordan even though everyone knew her and Jeff were together. That's real unusual. Usually, if the houseguests know that there's a couple and they are running the show, it'd be logical to get rid of one of them.