Interesting to see all the comments saying Yankees/Red Sox - I am a die-hard Yankees fan first and foremost that despises the Red Sox, but I've always heard the complaint that outside this area, many either hate both and could care less. Interesting to hear that's not the case. The other problem I hear is that they play too much for it to be meaningful, but it always feels meaningful when you are playing Best of 3 or whatever.
I mostly agree with Angus, especially if you are talking about New YS which is trash while Fenway is a landmark. The old one came close but mostly during playoff time. The location is so atypical for old-time baseball.
Re: bagelman's complaint - I think you have the stereotypes reversed. It's mostly classy and elitist New Yorkers vs. uneducated Bostonians and those across the country that want to turn it into America's team. Is there anything more stereotypically racist than a Boston baseball fan?
http://www.theatlantic.com/politics/archive/2015/08/a-trump-inspired-hate-crime-in-boston/401906/ I don't mean this to be rude to all Bostonians as much as I like to despise the place, but it's pretty accurate. I feel the richer Bostonians might be football and hockey fans. (The Patriots have their fans too but in the same sense the Yankees do. It's not the loud New Yorkers or Bostonians there primarily.)