Tough call. I'm focused on the Illoriaon right now, so they are becoming a bit more appealing. I know their current in-game status is kind of, well... blah. There new activated abilities, new equipment, and quests are going to make them really shine though. In 3.0 they will most likely be my favorite... until I work on the next faction's quests anyway.
I loved the Feron for a long time, but I've played them for so long in testing and post test that I'm worn on them. They are still a lot of fun though. Almost nothing beats seeing someone catch a fast flying axe to the head. Throwing weapons are one of my favorite, and most underused weapons, in any rpg or action game. I was glad to be able to make them a signature of the Feron.
So, in answer to the question, I enjoy playing all of them. Do I think any of them are perfect? No, certainly not. I am working on changes and new things to do with them whenever I have time. I think they all provide a lot of fun though.