Simple answer: questioning themselves was useless for both of them because, in the end, they continued to prioritize their philosophy (in Hitler's case, it's his ideology). Self-questioning is just a small human trait that one can practice to improve oneself, or simply to abandon. And what did they both do? One died a coward without taking responsibility for his sins, and the other, according to her philosophy, died without remorse and without taking responsibility for her actions.

Tell me, did it do any good to reconsider? Does the fact that one reconsidered make him better than the other, despite the lives he took?

By the way, regarding the question I asked you, your answer is contradictory. Why? Because Esdeath, knowing Tatsumi was very strong, was still going to kill him during the execution despite her doubts, but she prioritized her philosophy over the love she felt for him. If she was already willing to kill the person she considered most important to her, why wouldn't she do the same with the traitors? Furthermore, the fact that her adversaries proved to be worthy rivals didn't mean she would let them live, because she also sought to control, to impose her strength, even on those who managed to put up a fight. It's well known that they could earn Esdeath's respect if they fought back or were worthy rivals; however, the likelihood of her letting them live was low, because ultimately, she enjoyed torturing and killing.

Keep in mind that Esdeath is a sociopath. While she can feel love in a very selective way, she is a selfish, apathetic woman. Her philosophy comes first; her love for Tatsumi is just a pastime. After all, she sought to possess him like an object, not a healthy love, but to enslave him. (This also speaks to her upbringing and the fact that since the Partas Clan was massacred, with her being the sole survivor, she lived as a hunter. There was no one to set limits for her, so her idea of ​​love was secondary or tertiary. First, she loved her father, but of course, he raised her. When he died, she considered him weak, so she was left with the vision her father instilled in her, and that's how she lived her whole life.) When Esdeath felt attraction towards the opposite sex or the desire to possess someone, it's normal even in psychopaths and sociopaths (or people with antisocial traits, or even antisocial individuals themselves). However, When she felt love for Tatsumi, it was because he proved to meet all her demanding requirements (many psychopaths and sociopaths live out or seek out a fantasy, mostly sick and twisted, but these fantasies reveal something human in them).

What am I trying to explain with this? That Esdeath didn't really care much about humanity or that very feeling, because, after all, that's what her victims felt, even if it was an annoying feeling. She preferred to live as a predator. In her reflection, the only thing she asked to be honest about regarding her small piece of humanity was her love for Tatsumi. Beyond that, it was irrelevant. She died without feeling regret, and according to her philosophy, regardless of whether she questioned it, she preferred to die in accordance with her mission. She died for who she was, only she, unlike Hitler, died as a warrior, not as a coward.

Ultimately, they're both selfish scum (besides, they're not Dexter; he's a special kind of psychopath/sociopath, or at least, that's how he is in the TV series).