Making Sidious canonically the most powerful Siths ever is silly
I know it's done because he's an "original" character, but it greatly limits writer creativity and really makes one scratch their head when their appear to be some comparative feats from other characters that calls his dominion into question. Same goes for Luke and Yoda. How about just acknowledging that these characters are unquantifiably pretty powerful and leaving interpretations as to who is the most powerful up to the fans?