Bane has mastered the 7 forms, and knows how to beat people who use Jar'Kai/Double Blades. Plagueis is just outmatched in sabers, tbh.
When they use the Force, I see it being about even. How strong in Plagueis' lightning? We know Bane's can turn an armored man into ash as of RoT (without Orbalisk power) which means that by DoE he has some insane lightning feats. He has the cocoon of energy that he can pull up before a saber hits him, but after the swing was started, which causes an explosion, which admittedly did not kill either of them, it still threw Zannah about 30 feet. He also has the speed feats from the rain scene and from his fight with Zannah, where the two were hardly even a blur, nearly moving faster than the Huntress could see, and he was pwning her face in. And she is a master of multiple forms as well. Djem So vs Soresu, normally Soresu would win, but Bane just overwhelmed her.
He can crack ribs with a kick, which is also insanely hard. (Zannah fight, DoE, on Ambria, he cracked 3 ribs and she flew back 15 feet)