What makes Regina a better protagonist than Navier?
Crowning a spoiled prince (or second life of a trash princess if you're a novel reader) has very similar themes of prejudice and dehumanization that remarried empress has but instead of slavery that is still ongoing in the plot, it's the genocide of a matriarchal society of mages that look place 500 years before the beginning of the story, it's what motivates the antagonist, Anita/Evaldina to enact her vengeance against the female lead, Regina, her family, and the entire empire as a whole.
Regina is what I would call a combination of Heinrey and Navier, she's chaotic but she's also incredibly intelligent and knows her way around politics and diplomacy. That might sound like an insult to her writing when I compare her to those two but it actually isn't, quite the contrary, Regina is an amazing main character. Why? Because she's not meant to be viewed as a perfect, innocent, girl who is incapable of doing any wrong and everyone who disagrees with her is an EVILLL monster who deserves the most suffering imaginable!
No, Regina is an anti hero.
I mean, it's pretty obvious that she's an anti hero from the very beginning, she says it herself that her goal is to become an insufferable human as one of her many tools she needs to ensure her spoiled little brother doesn't end up becoming a push over and spell the empire to certain doom once he inherits the throne. She herself isn't interested in becoming an empress and even if she wanted to, the patriarchal society she lives in wouldn't allow her to be anything beyond a regent empress until Theore comes of age so in order to train her brother to become an emperor with a back bone, she sets an example by acting even more of a brat. How does Regina express her new found self? Why, by threatening to beat Theore the old fashioned way with a small bat, setting an entire castle on fire, breaking off her engagement to the side antagonist, and generally giving her hand maiden an aneurysm with her antics.
Normally, it would annoy me when a protagonist ends up being revered as a great person when they did something reprehensible because of some contrived reason that poorly explains why it was actually good on the the place. (Think of all the times a FL buys a slave for example) and while that does happen in crowning a spoiled prince when Regina is revered by a group of ill villagers because the castle she burns down was containing a plague, it isn't for the purpose of worshipping Regina, it actually plays a vital role that moves the plot forward.
Before burning down the castle with her love interest, Aaron, the audience is shown where exactly the disease came from, a spell that was cast by Anita by using the blood of a mother dog. This plot point isn't just dropped after the audience is shown that Anita did something evil, no, it makes a few more appearances that explain why this specific breed of dog naturally becomes aggressive near mages, because in order for the mages to access some spells, these dogs would have to be hunted down and slowly drained of everything until death.
And this is why I am not nearly as annoyed as I would be when Regina commits a crime and gets away with it, because while there may not be any consequences for HER, both she and the readers now possess more knowledge about the mages.
This characterization of Regina is what makes her a character I and many others still want to follow even if she is far from a good person, as vile as it was to see her purposely hide the evidence proving that the land her family rules was formed from a genocide of the very people the culture still reduces to stereotypes of ugly hags who want to harm others for their own selfish actions (To the point where "witch" became a slur used against Anita's peiple) it not only fits Regina's character well but it also reminds you once again that just because she is the protagonist, doesn't mean she is a good person, her goal is still to protect her family, friends and empire and even when she learns the truth about what her ancestor did to the mages, as much empathy as she feels for Anita, that doesn't stop her from her goals of stopping Anita from getting her revenge.
She's doing evil things for a semi-good cause, much like Anita does.
Now, compare Regina to Navier, unlike Regina, Navier can't see herself as anything other than the perfect empress who has been wronged by her husband and unfairly displaced as empress of the eastern empire. She isn't wrong for being rightfully upset when Sovieshu openly cheats on her and emotionally and verbally abuses her over her refusing to get on her knees for him and beg him to love her again. Navier too was a victim of domestic abuse and has been groomed by the adults before her to abandon her identity as a human being in order to be the perfect woman of the empire.
Navier not accepting that she's also a bad person isn't the problem, it makes for great material for an anti hero, but she isn't the only one denying that she could have the capacity to do anything wrong. The other characters also support every decision she makes, even if it is morally reprehensible, if a character is designed to be a "good guy" than they HAVE to believe in what Navier believes in, if they don't, then they're just an evil bad guy who doesn't want her to be an empress as god intended.
You can tell how these two narratives really see anyone who isn't praising their female lead based on how they write the villains.
Crowning a spoiled prince does have its fair share of criticisms related to how it handles its heavy topics. The narrative rushed through season 3 and for a genocide of innocent women, including Anita's mothers and sisters, it should have had put in more time to properly convey just how fucked up it was for the mages.
This wasn't helped by Anita's ending either, I will cut some slack for the author since the idea I got was that the first emperors apology to Anita was just bullshit but Anita accepted it anyway while admitting that she was still a pushover for doing so, the way it was presented made me feel that Anita didn't REALLY forgive her monster of her first love but she was also just tired and only had so much time left, she probably just wanted to spend the last years of her life with Herman, feeling loved and cared for even if everyone else knew her as a villain.
Still though, I can't blame the readers for being extremely disappointed in how Anita's story ended.
With all that being said: While it isn't perfect, Crowning a spoiled prince still makes a pretty good attempt at emphasizing WHY Anita is like this, you actually want to root for her over Regina, there isn't any justification for what the first emperor did, the world itself shows the readers that the society of the empire Regina is trying to protect is incredibly flawed in its thinking and most of all, every main character, good or bad, was made with love, no one was truly singled out and everyone could be rooted for in some way.
Remarried empress on the other hand, makes the choice of deliberately including slavery for the sole purpose of dehumanizing Rashta, not just within the context of the society the characters live in but within the mind of the writers who wanted Rashta to be so below Navier, that she would be treated like animal instead of a person, all because they hated her existence that they created for her.
Crowning a spoiled prince doesn't justify a literal genocide with "The mages were actually evil and needed to be stopped!" But Remarried empress does justify slavery, with the excuse that slaves only become slaves because they commited a great crime and when they are allowed freedom, they only want to take advantage of others and ruin the lives of many for their own selfish vendettas. The rare cases where slaves like Rashta aren't demonized as greedy creatures is when they serve nothing more but to show off why the protagonist is so great and why the antagonist is evil. Ex: Phix, Rashtas friend who helped her escape, who was hardly if at all mentioned before his one and only appearance where his entire purpose is to be betrayed and killed by Rashta.
Anita's backstory is shown to explain why she has such contempt for the empire. It was formed by stolen land and the bodies of everyone she loved and when she wakes up 500 years later, not only has nothing changed but the man who took advantage of her and murdered her people was celebrated as a hero while said people were demonized in the form of caricatures and repeatedly referred to as the equivalent of a slur. The author didn't give Anita that backstory just because they hated her so much that they didn't want her to have anyone who would love her, they gave her that backstory in order to craft a complex and conflicting narrative for the readers to decide who is in the right in that situation.
Rashtas backstory may have an actual effect on the plot but that "effect" is designed as something your supposed to laugh at her for as she continues to get belittled, humiliated, and out-smarted, and eventually, it leads to her downfall as she is forever remembered as a seductive wench who stole what belonged to Navier and tried to "sneak" her illegitimate baby to a crown princess position, forever being remembered as the eastern empires most evil empress as slaves will likely continue to suffer under more scrutiny than they already have been now that Rashta will be used as a justification for why slaves need to stay in their place, ensuring decades of dehumanization to come.
All because the writers hated a character they created because she represented everything they hated. Rashta could only ever be "liked" in a timeline where any character she might have once had has been erased in favor of blindly worshipping Navier.
And that is why Regina is a far better protagonist than Navier could ever hope to be.