What is a really fun free mmo?

I'm looking for a fun one mmorpg to play with my friend because school just ended! I want it to be fun enough so we stick to it!! I've already played wow, runes of magic, league of legends, lost saga, allods online, and eden eternal! Wow, lol, lost saga, and eden eternal were all pretty fun but they became boring after a while. Answers appreciated:D and please dont give me a website like mmohut. i want actual game names:)