Miami Heat:
The Heat have no one really that will make them contenders this season, even if Dirk signs. Dirk in Miami may bring them a playoff glimpse, but not anything close to what Boston can offer. We have a ton of scorers and most importantly Dwight Howard. Miami has some talent, but Gay and DUrant are WAY WAY to raw and they wont have a shot at anything for at least 3 or 4 years.
San Antonio Spurs:
They have Oden, and nothing else. Their city isnt anything special, and they have no shot at the playoffs even with Dirk, only thing that gives them any hope is that they are in the West....title...come on now.
Washington Wizards:
This team was good last year, but not great. Now all they have is Peja, and they still need to sign like 10 players to get to the roster limit. Will they have enough money to sign Dirk and then ALSO sign role players? No way, and this should eliminate the Wizards right away. Their starting center is Aaron Williams.
Indiana Pacers:
They have Lamar Odom and then a TON of rookies. Its not even obvious who their second best player is because half the roster hasnt even played a game. They will not make the playoffs in the near future. They to need veterans and dont have cap to sign Dirk and then get enough pieces to compete.
So you see, Boston is the best place for Dirk...the only place.