For me, its because Liverpool and Man U were always the big teams when I was growing up. They have the heritage, history, trophies, famous old stadiums and I guess they belong at the top in my mind. Man City on the other hand are just a rich Arab's plaything. They've just thrown money at the 'project' and its won them trophies. Almost like a chavvy lotto winner moving into Knightsbridge, they don't belong there.
What i've written is very subjective to myself but that is how i see it. I know football has changed over the years and if Villa were taken over by a rich Russian or Saudi then i'd probably love it, but who said opinions in football need to be consistent.
Same here. Liverpool were lowly second division club until Shankly built them up. So they were a big club even before money took over the game. United the same, the Busby babes and all that. City did have a period under Mercer and Allison where they won the league but until the rich arabs came along they were smaller than us and thats why I begrudge them.