2/3: For me, Vitiate's definite #2 while Plagueis is either 3 or 4, (behind or ahead of Krayt, idk,) but that's cool.
Well, he said Vitiate. That could mean he's going down "Valkorion's not a Sith" bandwagon and talking novel Vitiate.
6/7: Agreed, but not sure if Vader is this high or not.
He is, tbh.
8: Nice addition to the list, and an accurate one too, but not sure he's above Sadow/Muur/Ragnos/Nadd/Hord/etc.
He may be. Even if he's not, SOR is; and he's a quasi-Sith too.
9/10: Ragnos should probably be above Darth Revan,
Not sure what evidence there is to support this, at all.