Aizen vs Ichigo is possibly the best fight within the whole of the Bleach universe. If you can remember every second of the fantastic fight then you’d remember that Aizen had been forced to get angry and upgrade into many of his forms in order to get into Ichigo’s level.
Ichigo’s reiatsu had completely vanished. Aizen expressions to how Ichigo’s Spiritual Pressure felt was that Aizen had thought that Ichigo was not even powerful to be sensed as a threat, but after Ichigo’s brute force was shown, Aizen was surprised to see that they have both ascended into something more powerful!
The fantastic image was drawn by Darkartmind87, they’ve got some fantastic art work which you should watch.