I'd have to go with either of the last two World Series runner-ups. The Rays in 08 or Rockies in 07. The Rays went from perrenial laughing stock to a team everyone thought would keep failing but persevered and won the AL pennant. The Rox september and october run was nothing short of amazing. I'll never forget skipping class to watch the win or go-home make-up game and Matt Hollidays phantom game winning run.
