I don't know.....the Wrangler Rubicon is very capable as well.
The key area where the Powerwagon surpasses the Rubicon is on the inclusion of a winch. Note, I said 'factory prepped'. YES, it is very easy and quite cheap to install a winch bumper and winch on a Rubicon which would bring its capability past that of the Powerwagon (shorter wheelbase, mainly), however, that JEEP would now be considered modified, and no longer to factory spec.
I guess it depends on the situation, too. The Powerwagon probably wouldn't make it over an obstacle a short wheelbase Rubicon would, winch or not. I'm thinking here of something on a purpose built off-road trail. That being said, if you're in the back woods on a very poorly maintained logging road that has been washed out, the Powerwagon will be my choice!
Give me my bag of chains and straps and a Hi-Lift jack kept under the rear seats, and a chainsaw with some fuel/oil in the bed, and that truck will be unstoppable.