Having boxed in warcraft, a very large thing for me will be how boxing friendly is the game?

The complexity/power of the macro system will be a consideration.
And how strong (easy to use) the follow system is.

The default WoW interface is very lacking compared to most games.
But then you can use addons to modify it greatly, which is good.
Addons really make the boxing of wow so much easier.

In the past, I'd evaluate an MMO from a solo player point of view.
I doubt I'd even try another game like WoW, if you could not box it.