I was searching for sandbox MMO with player driven economy, but in everything I found, the only real end-game purpose was PVP which, alone, gets boring fast. Also, in many games, the multiplayer element is boring, since you only use others to form parties to complete the standard quests/dungeons.
Sure, CoE has many interesting features, but the truly unique feature in CoE that piqued my interest is the player-driven story that is being developed in these 10 years. Other players drastically affect your own story, not just forming raiding parties. It kinda feels like playing these non-lineal RPG games like Witcher and Skyrim, with the difference that it is MMO and there aren't just multiple choices/endings: There are endless possible choices/endings.