Tbh I don't think Sheev is matched by any other Sith in history. But I do want to know where Nihilus fits into this, personally. Especially since he hasn't been mentioned AT ALL yet. I get the impression that he's a lot more powerful than most of the ancient Sith. Kreia herself says that he learnt the "greatest" of the Sith teachings. Which I assume means he learnt how to drain the force, though the drawback is that he loses control over the force and hunger ... it controls him. Then again, this control over him already started when he realised that killing someone and draining them made him even more hungry.
Kreia also says in the Dark Side route that Nihilus' power will /only/ rival "some of the ancient Sith" so he does know the Siths greatest tech but raw power wise is still below at least the Ancients Kreia mentioned. She said this in the DS route of tth Jedi enclave where you kill all the Jedi masters.
Palpatine>Ragnos>Nihilus.
Well luckily I've started a Dark Side character, very keen for the Kreia talks throughout the game ... very well the best written Star Wars character imo.
Anyway, I guess the implication by Kreia is that it is the "greatest" of Sith teachings, but also that raw power can overturn him, IF it's massively strong enough. So like, Sidious level basically...
I can just see Sidious creating a black hole and swallowing Nihilus in it.