IMHO, Bane would lick the floor with Bandon's corpse. 😛
Honestly though, it does seem quite one-sided:
-Bane was a true Master of the Sith, and he wasn't just a stupid power-hungry war-monger like all his predescessors. I mean, he was at least smart enough to realize that there could only be two true Sith, or else the Order and the teachings would die, and the Jedi would win.
-On the other hand, Bandon is a largely undefined and undeveloped Sith Apprentice, usually easily hammed by your Revan character in KotOR.
So....Bane for me. 😉
what would be better would be Bane vs Malak or Bane vs Revan, but for Bane vs Sidious I would say Sidious, for Bane vs Bandon, well I don't know enough about Bane, but Bandon was killed pretty easily my first time, a decent fight in my second time through, I lost actually 2 times in a row my third time through and now in my forth time I wasted him. But remember, the character is Revan, he would waste almost everyone, and Bandon did kill loads of Jedi and he would have been a match for many more Jedi and Sith. But still I say Bane here because he was a Sith Lord and fully trained, if Bandon was fully trained, maybe, but not the way he was.