im starting to lean towards kenobi now, considering he prolly has the edge in sabers (bane has NOT beaten anyone noteworthy with sabers, other than featless kas'im, who probably isnt obi wan-level, or at least hasnt mastered trollesu to the extent obi-wan has.)
in the force, bane most likely takes it, due to some pretty powerful lightning (although obi wan could prolly block it), and his powerful telekenesis, although the force competition is not nearly as lopsided as people think. ultimately, obi wan wins, due to his impeccable defense (can block blaster bolts from entire armies) coupled with his saber mastery and overall skill.
Kenobi seriously does not have an advantage in sabers. Bane was so fast that he was able to appear to wield a dozen lightsabers to Zannah, who herself is a powerful Sith Lord. He's also moved quick enough to appear invisible to a hall of trained Sith, including Kas'im by the way, in that it took a second for them to even register that he'd moved. He's also blocked and dodged out of the way of every raindrop in a howling storm for a full 20 minutes, displaying incredible skill and speed. In terms of skill Bane memorised hundreds of thousands of sequances in a few short months, amazing Kas'im with his progress. He defeated a swordsman greater than Kenobi, through his sheer power and lighsaber knowledge. Obi-Wan has nothing to challenge him with.
Obi-Wan can NOT block blaster bolts from entire armies and the Force competition very much is as lopsided as it appears.