What quest or questline is the most memorable?

MMO quests are old hat by now, and the vast majority of them are some slight variation on the standard kill-10-rats or FedEx mission. Some are unique, though, in terms of both their rewards and their mechanical presentation.

I'm thinking of EverQuest II's betrayal quests here, which allow you to switch factions, home cities, and in some cases, even classes. What MMO quests or questline do you find the most memorable and why?

TH

I liked all the story ones in MxO. Nothing has come close to that for me since, not even the SWTOR story.

All other questlines I consider filler...