They're both quite a bit higher than Revan, actually. Proof was in the New Essential Chronology.
Evidence: firstly, so noone can argue the canonicity of this, from Leland Chee's own log and Q/A and I have other links
C-canon is primarily comprised of elements from the Expanded Universe including books, comics, and games bearing the label of Star Wars. Games and RPG sourcebooks are a special case; the stories and general background information are themselves fully C-canon, but the other elements such as character/item statistics and gameplay are, with few exceptions, N-canon.
And the link to the source itsself: http://img384.imageshack.us/my.php?image=proof9gs.jpg
Palpatine might be the most succsesful Sith, but he is by no means the most powerful. Exar Kun could PWN him in a heartbeat, Ragnos would PWN him in an eyeblink. (I think thats faster than a heartbeat, Im not sure tho).
But please, don't turn this thread into an argument about whether your info is N-Canon or something like that.... PLEASE!