IMO, yes. Not sure about Bane though, but Exar Kun definitely could. He was living at the time where the Republic was constantly at war, he slaughtered many Jedi, so he definitely has more battle experience than Sidious, who hid from the Jedi for most of the time. It took a whole ton of Jedi to kill Exar Kun, and even then, his spirit still survived, and his spirit, ionized air particles, took about a whole ton of students of Luke Skywalker to kill.
He's a politician with no talent for fighting a nice command of the force but many Ancient Sith match that and most surpass that. They have done more impressive things, have more experience with fighting and have done a lot more impressive shit then Sidious had. When they tried fighting for control Sidious was sneaking around using politics. Impressive but nothing that would make you think he is a great fighter, just a politician with a good command of the force.