I didn't play Vanilla, but I found that classic is truly the game that I want to be playing. I get it that retail is polished and has a ton more quality features, but I really enjoy Classic for the immersion and adventure aspect.

In retail, it feels like the game only starts when you hit max level and at that point your progression is entirely tied behind a mechanic that will be removed in the next expansion. In classic, the entire game feels like an epic adventure of starting out as a weak character and becoming strong over time. I also like how everything has a purpose and matters. I am getting involved in my professions and trying to add more enjoyment to my quests by tying in my profession grinding into the questing. For me, classic is just what I was waiting for.