Gillette is nothing like the old Sullivan Stadium, where fights happened like every 5 minutes (in addition to public urination, mostly because the bathrooms didn't work, but I digress). Given that Gillette is now about 95% season ticket holders, the fear of losing your tickets is real, so generally Pats fans aren't getting into brawls.
I've said for years the absolute worst fucking fans that come into town are Dolphins fans. On Sunday night, I was in 129, and surrounded by Dolphins fans, in the row in front of me, and row in back of me. The ones behind us were fine, the ones in front of us sucked, doing their Fireball shots from nips at kickoff, throwing the Dolphins shark sign (picture someone making an L for Loser on their forehead), just taunting away at Pats fans. And they've been like this for over 20 years. They show up entitled, like they've been on a 20 year run of dominance, talk nonstop shit to anyone who will listen, and then generally slink away when their team is losing.
When the Pats fans started booing the offense in the 1st half, these assholes were like "you guys are the worst, we'd never boo our team in Miami, blah blah blah." My immediate response was "That's because nobody in Miami is there to watch the game." They were young, and drunk, so it didn't get ugly or anything, but if I was someone else, or the guys around me weren't long time season ticket holders, I can see 25 different moments where there could have been a fight with these guys (they were in their early 20's, best guess, 4 of them).
Jets fans just get pity, nobody cares about them. Bills fans are great. They show up year in and year out, usually with the strongest showing of any opposing fans, knowing their team would get their asses kicked, but they loved football, loved their team and were always amazingly courteous and making friends and talking football. It's one of the reasons I find myself rooting for the Bills nowadays when the Pats are out of the hunt. I'd rather see the Bills win over just about any other contender in the AFC.