Aizen. While Ichigo had trouble fighting Grimmjow, Aizen forced the latter to his knees with Reiatsu alone. Although that's just me not knowing all that much about Bleach.
Ichigo, his was so high you couldn't even feel it.
The Ichigo who fought Aizne has a lot more Reiatsu.
But Aizen > Base Ichigo (in Reiatsu)
Didn't that ichigo give up almost all of his reiatsu for phyisical strength?
Didn't that ichigo give up almost all of his reiatsu for phyisical strength?
Didn't that ichigo give up almost all of his reiatsu for phyisical strength?