>>715982468fuck no don't play on retail, it's an awful experience for a new player, you get weaker as you level and the game does not adequately teach you how to do things.
classic anniversary is a good option. it's currently in the original vanilla state of the game and will progress through expansions over time. it's basically a "restart" of the original version of classic, which is now on mists.
you can also check out mists if you want, it's hitting in like two days and was a popular expansion. it's a lot less time-consuming to get to max level than vanilla.
imo, if you want something extremely time-consuming, go with anniversary, if you want something more casual, go with mists.