It is Real Madrid and Manchester United.
Many sports fans are passionate about their sport and their favourite team. So there is no real answer to this question. Traditionally football fans sing at most grounds and support their team for the length of their lives. Football teams around the world have an attachment to the area and cannot be moved. However cricket fans in India are passionate, in usa gridiron and baseball fans are noisy and care for their favourite team, as do ice hockey fans in Canada. So no one sport has all the most passionate fans. Football has the most fans around the world and thus the highets number of passionate fans so if that is what you were asking, which sport has the largest number of passionate fans, then the answer would be football.
Probably Manchester United, they have millions of fans in Asia.
The Great LIVERPOOL FOOTBALL CLUB
That is debatable. Michigan has had the most fans in a stadium in a game, and there are fans growing everyday.
Persepolis is the greatest pro football team.
The Dallas, Cowboys are the best football team in the world forever and ever
PSG by a long distance