Cataclysm it is. It started out well with the first tier of raiding, excellent stuff. Then we had Firelands, far too small a raid for 6 months farming. Then Blizzard follows up a small raid with yet another small raid in Dragon Souls that also had the most boring/underwhelming/ridiculous end boss in the history of WoW (not the mention the entire zone was almost 100% entirely reskinned garbage). You can probably blame the implementation of LFR for the lack of content tbh.
TBC>>>>>>>>>>>>>>MoP>Wrath>Cata>Vanilla. From a 100% raiding PoV.