Oh, I love it when people read the thread before posting :roll:
After reading the Revan book...I don't care what Lucas said...Darth Vitiate is the most powerfull Sith have ever been. FFS he was able to "eat" the force and life of an entire planet and almost did the same with the whole galaxy (the Knight stops him just in time). So no...Palpatine is a mere insect near Vitiate.
Palpatine > Vitiate. We all know that story, we all read Revan, we debated, and we decided Sidious is still stronger because this thread is Raw Power.
Vitiate accomplished that through a ritual, with 'willing' sith, while Papa palps quite literally destroyed fleets with his raw power. He probably could have done that ritual too, if there were more sith, and his goal was to be alone in the world. But no, his goal was to rule the galaxy, can't do that if everyone is dead