I'm with Zet, most fun raiding I had in WoW was BC, with Wrath being second (Ulduar probably being one of the best raid tiers period). Starting in Cata, (though this may be bitterness with the fact my guild was falling apart as the inmates were running the asylum) just didn't have the same feel, and for the most part seemed a lot easier versus Kael, Illidan, Brutallus, etc.