Ahsoka wins, imo.
Originally posted by TgKWindRenegadeBane was indeed a prodigy -- one of those at the Korriban Academy who was touted as the possible Sith'ari when he initially arrived, in fact.
even as a sith in training bane was hailed as a prodigy at the academy, bane is also seen as a prodigy in both lightsaber combat and force abilities having a natural affinity for force lightning.
However, Bane lost all of his 'Sith resolve' in the wake of his battle with Fohargh, and as a result, his abilities/skills plummeted astronomically across the board. So at the time Bane first battled Sirak, he was a sad shade of the man he'd previously been/would become. It wasn't until after his loss to Sirak that Bane began to truly realize his potential.