As most ppl said, epic is very subjective. But some things stand out. Epic is when you have 300+ lvl 1 naked orcs trying to raid Stormwind. Epic was pre-Wrath zombie event. Epic was opening of gates of AQ....
This can be subjective but try to answer. Which is more epic - getting to Illidan on top of Black Temple after a long journey or queing for Lei Shen in RF to get ported in front of him with 2 stacks of Determination, 5-6 people missing and quite a few of them arguing who's momma is fatter or who is baddie?
---------- Post added 2013-04-20 at 04:47 AM ----------
*edit Oh, and Kil'jaiden was most powerful boss we fought so far, would be a shame that he didn't overshadow Illidan (which was awesome). IMO.