[Eurytus]

OK, this is going to be my last post on the subject as we are not going anywhere. It states in the book that the captains of the West could see that the Mouth thought that he would be the lieutenant of Isengard and would be the tyrant over the tribute realms west of the Anduin. The Mouth hints to as much.
This post would quite obviously be the second most prominent after Sauron in Sauron's new world order. The tribute realms would after all provide much of the products for Sauron's realm and the man commanding their distribution would be powerful indeed.

Nowhere in the books is any indication at all given that the Nazgul would obtain any position of command in Sauron's new world order. None. That just leaves Gothmog about whom we know little.

The only logical explanation is that the Mouth is the most likely candidate. I would suggest that it is not I that is letting my intepretations govern my opinion. Mine is based on Tolkien's only writings covering the issue.

Yours seems more based on a perception of the talents of the Nazgul and is not backed up at all by the text.
I have little doubt that you will keep this opinion but to my mind it is based more on the perceived combat effectiveness and 'power' of the Nazgul than an accurate intepretation of the text.

The fact remains that, given what little we have in writing, we have to expect that the Mouth would have the position of most influence and power after Sauron in his re-ordered realm.