A recent Harris Poll asked U.S. adults to name their favorite MLB teams. Not surprisingly the Yanks and Red Sox top the poll. Those east coast rivals are followed by the Braves, Cubs, Dodgers, Cardinals, Phillies, Tigers, Giants and Mariners (whoo!).
This poll shouldn't be taken too seriously, however. Only 2000 people participated, which is too small to make a lot of declarative conclusions. For example, the Angels came in as the third least-favorite baseball team. I'm sorry but that's just wrong. There's no way that such a successful team with a large fanbase (taking some Dodgers fans with it) is less popular than the Marlins or Nationals.