Anakins revenge, but you have to take into account that Sidious could have been going easier on windu as a result of him knowing that anakin would show up, pretending to be all hurt and stuff, but after mace is hurled out a windu, one might observe how the emperor just hopped right back up really, so I have no doubt in my mind that Sidious would take windu.
But I defiintely had to give this to yoda, a master of Lightsaber III technique, he, along with dooku were the only ones to ever beat Windu when sparing, and Yoda beat dooku, so the answer is clear in my mind, and besides, Yodas my boy.