If we assume a nexus setting, Darth Zannah can use it to gain advantage like she did against Darth Bane; Zannah conjured (sorcery-oriented) dark tendrils to overwhelm Bane.
I am sure if Darth Wyyrlok III have an answer for (sorcery-oriented) dark tendrils or not. But since he is also a good Sith Sorcerer, he might have some tricks up his sleeves too.
Therefore, I believe that both can win under right circumstances.
Wyyrlok is more skilled and has more offensive powers to use, he wins.
__________________ "Happiness is a lie. Life is horror. The light is always dying all across the universe. The last star will flicker out someday, when it does, all that remains is shadow. And I will be its king!"'-Amahl Farouk