Boston and it's not close.
Whose ends to the season is going to be remembered a decade from now? Only the Rangers, Braves and Red Sox. The Rangers will be remembered only as the WS opponent for one of the great comeback stories of all time, not because of their own heartbreak. That leaves the Braves and the Sox, and between the two, the Sox had the bigger payroll by far, greater expectations by far, choked it away to the team with the smaller payroll by far, had the bigger lead going into the choke, and lost it in more dramatic fashion on the final day.
Oh ... and then the team did further damage to its future when someone anonymously trashed the players and manager in the media, adding insult to injury and making it a less attractive destination in the future.
This shouldn't even be up for debate.