I remember this question being asked a few years ago and the general consensus was Sting. Go back to the mid-2000's and many people would argue it was Daniel Bryan. I'm sure @Vaderbomb even threw Fergal Devitt's name somewhere into the conversation at some point (I could be wrong). In recent years though, all of these guys have competed inside a WWE ring.
So, who is now the greatest wrestler to never compete for WWE?