I would highly disagree with anyone saying lich king was the best expac, I get the feeling that people who say this were not present for Burning Crusade, Yeah, lich king had more players, but that was because people were still coming aboard after the impression that TBC left, And lich king was the beginning of the end.
The game was so dumbed down by the time lich king was half way through it's life.
The game is no fun when you can pug EVERY raid on ANY difficulty.
I used to run every raid available on 3 different characters in one day.
Prior to lich king, you would be lucky to complete a raid dungeon before it reset.
Classic coming back is the only thing that can save this game, the state it is in now is garbage meant for 13 year olds who use daddy's credit card to get a max level character.