It always changes, every season. A good example of a team up and down is the 2009-2010 to 2010-2011 Cleveland Cavaliers. In 2009, Cavaliers were on top of the world, but in 2010, they finished 19w-63l. An average win of .232. Along the way, Cavaliers set an NBA history record of the longest losing streak, 26.
The teams that are usually good are the Boston Celtics and Los Angeles Lakers. This year (2010-2011), the San Antonio Spurs excelled way over their usual ranking. So you never know when your favorite team might shoot through the sky.
In 2012, the Dallas Mavericks are the defending champions. There is general agreement that the Miami Heat has the best team on paper, but they don't play the games on paper.
miami heat is the best team in NBA
LA Lakers is the best NBA team today
At the moment the best team in the NBA is the Los Angeles Lakers but the best team ever has to be the Harlem Globetrotters
Miami Heat is the best team
The best team is the Lakers.
Lakers and Celtics
the Houston Rockets are the best team in the league
the bulls are the best team in the east.
the best team in the NBA over all the years are the Phoenix Suns
The best team in the NBA history is Phoenix Suns.
The Los Angeles Lakers used to be the best team in the NBA with two great players - Kobe Bryant (currently the best player in the NBA) and - Shaquille O Neal (was the best center in the NBA.