Aizen without contest... sorry to say but thats the damned truth. the Fullringer Arc made it look like Ichigo was having a tough time fighting when he didnt have any power to gaining his Fullbring ability which brought out only a fraction of his power. (yes im getting to the point) Then once Ichigo had his Fullbring Ability stolen, he immediately was given his Shinigami powers back and pretty much beat Ginjo's little behind without effort.