Ask an Everton fan and he/she would probably say Liverpool. Ask a Man City fan and he/she would probably say Man Utd. Ask a Spurs fan and he/she would probably say Arsenal, but might say Chelsea. Ask a QPR fan and he/she would almost certainly say Chelsea.
There is not always reciprocation though. For example, how many Chelsea fans are going to pick QPR? Let's be serious! And most Liverpool fans would probably say Man Utd, not Everton, for example.
So, out of curiosity, who are the clubs you dislike the most - and why?
My top three:
Liverpool - lived near there growing up and received endless abuse for supporting Chelsea, ghost goal, Scousers
Man Utd - too much success for too long and dislike Ferguson for so many reasons I wouldn't know where to start
??????? - don't really have a third!