Originally posted by Nephthys
Do people put so little stock in Vitiate's statements of being more powerful than Nihilus?
Vitiate is more knowledgeable about the Dark Side than Nihilus. Vitiate is older, wiser, and is capable of more than Nihilus. His ritual on Nathema and his planned ritual for the entire galaxy is IMO magnitudes beyond what Nihilus could achieve.
The main reason I place Nihilus above Vitiate in straight-up combat is that his powers aren't rituals. They seem to be his own raw power. And I don't think any being could match Nihilus' drain without becoming another Nihilus themselves. His life drain and his TK are beyond what we've seen Vitiate perform in combat.
Now Vitiate's lightning is very impressive, quite possibly the most impressive aside from Sidious. If Vitiate could resist Nihilus' drain, I personally still think he would not be able to counter Nihilus' TK.
Nihilus almost overwhelming the Exile and her party after being weakened is probably less impressive than Vitiate holding off the HoT (not sure, never cared for TOR), but it shows that if it (LOL) came to sabers, he would be able to hold his own against Vitiate's illusions and other tricks.
Overall, either one could potentially win depending on the circumstances, but I'd lean slightly towards Nihilus.