I'd vote for Rift, too... it really is a WoW clone!
Addons aren't as good or as various as you can find for WoW and the macro language is a bit simpler.
Be aware, though, that it is a bit heavier on PC resources than WoW.

Avoid GW2 for boxing - they have all but banned it... http://isboxer.com/forum/viewtopic.php?f=41&t=4014