While I love the WLK and loved TBC more than classic wow and WLK brought a lot more to the gaming experience I have to say my most enjoyable times were in Vanilla, purely because everything was so new. The desperate climb to get to 60 that seemed to take months, meeting new people that had patience for each other because everyone was in the same position.

Late TBC and WLK a lot of that has been lost. Not the games fault, it's purely because I've played this game for 5 years now. :P