Seems like every team in the league has some sort of history with the cowboys.
I looked at a ton of old and new rivalries and different fans opinions and thought "wow the cowboys have a lot of rivals"
Obviously everybody in the NFC east hates them.
But the 49ers used to have a huge rivalry with them.
Saints fans I've noticed are pissed at them for ruining they're winning streak in 2009.
Steelers hate them for the SB rivalry.
Packers fans hate them because they're basically the polar opposite of the cowboys in fanbase and system.
Raiders fans hate them but they hate everybody.
Bills fans hate for beating them in the SB.
It's what happens when the media ordains you "America's team" when you haven't done much lately to deserve that title...