it matters where you live. Since i live in New York i am going to say the best football team is either the giants or jets, and the best hockey team is either islanders or rangers. For baseball it is different because the best team is obviously the Yankees.
Well there are tons of New York sports teams. New York Mets, New York Yankees, New York Red Bulls, New York Knicks, New York Rangers, New York Islanders. But I'd say the Yankees are the most popular, since they've won the World Series 27 times, which is the most times a team has won the WS.