When I started this I thought the SI storyline ends with you being Darth Nox. I didn't know there were other names you could get. How does that work? Anyways, what I meant to say is canon SW vs. canon SI.
With the some Emperors power infused into the Wrath (if so) plus his own force abilities vs. the SI's force ghosts and own ability...their force abilities will become equal. Then it will come to lightsaber combat, which all epic star wars duels end in. This is where the Wrath is superior.
And as has been brought up... neither would win.
Darth Nox is immortal through the ghosts that now fill him.
The Wrath is supposedly immortal through the Emperor.
Unless the Emperor knows a way to subvert the ghosts powers, or the ghosts know a way to subvert those of the Emperor... well, it'll just be a bunch of endless combat.