I'm gonna give it to Kao. Rahn was skilled and powerful no doubt, a good fight for anybody for sure. But he was killed by an Inquisitor, albeit Jerec WAS the most powerful Inquisitor (still don't buy that Jerec=Vader bullshit though.) But I digress, Kao wins.
EMP
EmperordmbLSDMB
Rahn was roughly Jerec level in the force because their presences rippled against each other and Jerec oneshotted Rahn, proving he needed his most powerful attack to best him #EvannovaIsNotABiasedIdiotGoddamnIt