While there are a number of similarities connecting Berserk's Griffith beyond the "hero goes bad" plot line, even Griffith would be shocked by the deviousness of Aizen's Soul Society betrayal.
Prior to the Eclipse in Berserk, Griffith was a hero, at least to Guts and the other of the Band of the Falcon. Despite not considering them his true friends, Griffith was undoubtedly dedicated to their well-being and did what he could to help them as if they were his own family. This is best illustrated in how Guts and the Band simply let him live or die as he wanted to, the Eclipse would have never happened and Griffith's darkest side would have never been tempted out. That is, while Griffith's betrayal was a heart-crushing shock, there were a number of external factors that influenced his decision-making.
As surprising as Griffith's betrayal of Guts and the Band was, Sosuke Aizen's was even more brutally shocking. Like Griffith, early on Aizen had a dream to rule over his own kingdom, namely to replace Soul Society leadership with himself. However, unlike Griffith, Aizen never faltered in focusing on what he wanted, nor did he consider the possibility that other means might satisfy his desires. Put another way, once Aizen made up his mind to foment revolution in the Soul Society, he did not let anyone or anything stand in his way or otherwise disrupt his plan. Each interaction with his superiors and subordinates, and anyone else deemed useful to his mission, was based on his lies to push his ultimate goal. Everything was calculated and premeditated.
The best demonstrations of the different levels of deviousness between their betrayals are provided in Berserk chapter 73 and Bleach chapter 316. In the Berserk chapter, as Griffith is coming to the realization that the prophecy of the beherit is coming true, he attempts with all his might to warn Guts and the Band to stay away and not touch him. Realizing what is about to happen, Griffith tries one last time to get his friend, the one who left him, out of harm's way. In contrast, in the Bleach chapter, readers learn that Aizen has been planning this betrayal for decades, slowly putting into place the pieces, such as having Captain Shinji Hirako choose him for lieutenant knowing full well that his arrogance will give him opportunities to move without anyone being the wiser.
While Griffith certainly leaned into his deviousness after his betrayal is accomplished, there was an instant in Berserk before it happened where he did all he could to stop it from happening. Conversely, in Bleach, there was no need for Aizen to lean into anything. His deviousness was certainly present at the creation of the betrayal, and more than likely was the root cause of it. There was never a moment where he had second thoughts or considered that what he was doing was wrong. Instead, he carried out each step with brutal effectiveness, never looking back, never pulling his punches nor hesitating. Aizen's betrayal in Bleach was not influenced by an ancient prophecy, like Griffith's in Berserk, but rather by his stone-cold heart.
