You know what forum poster Timat is talking about. Those quests that you died a half dozen times attempting to complete. The quests that took hours of travel or multiple dungeon runs to complete. The quest that you completed after it went grey in your quest log simply because you refused to let the quest beat you. Posters in the thread already have some suggestions: the druid sea form quest, the Onyxia key chain (both horde and alliance versions are a nuisance), and, of course, "Vast Ocean, Deep Sea."
See more player opinions in previous forum posts of the day.