The Buffalo Bills. I grew up in Central NY.
Before Thurman Thomas and company came along, you couldn't find a Bills anywhere. Their stadium couldn't draw fans if Ralph Wilson levitated and was passing out $20 bills (which is coincidentally about the same price Ralph paid for the team)
The NFL fans in that area were:
1. Giants fans
2. Cowboys fans
3. Dolphins fans (for some odd reason)
Then once they started winning, everybody became a Bills fan. And where I'm from you either love the Bills or hate the Bills. And it's a widely held belief between me and my friends (also Bills haters) that about half of the Bills fans are just old Giants fans that got sick and tired of rooting for them.
Despite that, they would claim Dallas fans are "bandwagon jumpers" when in fact there were more Dallas fans than Bills fans back in say...1985. Dallas was almost always on TV back then up in NY and that's a good reason why so many fellow NY'ers like myself grew up Dallas fans.
I like how they claim that they treated Scott Norwood with respect when he missed the FG against NYG. In reality, they threw the guy under the bus and wanted him out of town immediately. Then there's the revisionist history behind the Flutie/Johnson debacle where the majority of fans actually turned on Flutie. It wasn't until they were proven wrong that they claimed they liked Flutie all along.
They also threw Bledsoe under the bus as well, but that's becoming hard to do since Bledsoe is far better than what they had to offer last season.
I also hate the Niners as well, but since they've sucked so bad lately, I can't take too much stock into hating them.
Rich.........