Runescape was better when it was 2D, the 3D rubbish threw me off the game totally. I got bored with WoW last year, and I still am, I tried WAR Online and that was just as bad. Neopets, I only go on there for the dailies, it just gives me something to do. Habbo, I rarely go on there anymore, and if I do, it's to chat to people.
So I'd have to go with Runescape, I was a loyal member on Runescape since 1998, and then 3D threw me off.