I've got a soft spot for Arsenal actually. Never used to, but Wenger plays the beautiful game and gets up Baconface's nose so I like him.
As for hating another club, nope - I save all my hatred for those bastards.
Like many others I dislike Spuds and Everton, but I detest any manager that tells his team to play the long ball (Pulis and Allardyce etc).