To repeat what others have said, it depends.
Even with the best home theater setup, you don't get the experience, the sense of being part of the community. Getting closer to the stadium, the tension builds, the hopes are high when you see others wearing the team colors, converging on the stadium. A little bit of tailgating and kibbitzing will really get you in the mood.
In the stadium, waiting for the game to begin, you can swap stories with the people sitting around (who you've never met before, and probably never will again, but who are your buddies because you all are obviously rooting for the only team worth rooting for!) about games past.
With the roar of the crowd at every twist in the game, you get totally wrapped up in what's happening on the field. (At home, the telephone may ring, someone may be at the door, and during one of those oh-all-too-often commercial breaks, you just might happen to notice some chore that has to be done, getting you off your focus.)
Along the way, you can keep second-guessing with your new buddies every change in the line-up, every call by the quarterback, every mishandled ball.
And after the game, if it's a win you can congratulate yourself for having been there, because obviously it was your support which turned the tide against the opponents. (Really, the manager should have come out and thanked you personally.) The good mood in the crowd as they stream out of the stadium will stay with you all the way home.
And if it's a loss, well, a few beers in a bar on the way home with your buddies (or just in the company of the barkeeper) will straighten things out. You can shake your head at the boneheaded decisions, any one of which may have cost the game.
Next morning, you can read through the pages of analysis in the local paper, knowing that you were part of that experience, and reliving the high points.
As for the alternative?
Staying home and watching it on the big screen makes a lot of sense if:
- the weather doesn't look that favorable (my dirty secret: I've shocked my Chicago hosts by saying no to seeing a Bears game in the pre-2003 Soldiers Field - they couldn't accept my argument that having a bad cold was an acceptable excuse for not going, especially since it was a balmy twenty degrees)
- you get a party together,
- or, quite the opposite, you're on your own and just want to take it easy,
or - and of course with the Yankees and the NY Giants this is only a theoretical possibility
- watching your team stumble in the standings is something you just don't want to see in person.