For me it's changed over the years and it's based on who we are competing with, done us a disservice or who have shite fans.
Originally was the Rags, Leeds and Spuds, then Everton came in to round out the top 4....Howard Kendal to blame
Never hated Liverpool, merely disliked then back then.
Nowadays.
Rags, purely for their self entitled wank fans.
Dippers....stuck in the 70s, Always the victims, never their fault.
And every other club when we play them....apart from Sunderland, as they have a class fanbase