FF11 is amazing because it introduced hard core PVE and game uniqueness and AION has a super efficient UI as well as incredibly fast super efficient game play and skill execution. WoW hit the ceiling utilizing every aspect that makes an MMO enjoyable hence it's enormous player base to speak for that fact and there are much much more.
BUT WAIT
Why would SE ever want to take in any one of those successful aspects? Apparently it's because they want to make a "Different Game"? well they sure as hell did lol... and it's not a pretty one at that.