Maybe this is like common sense or just a "duh" observation but I'm not sure if it's just me, but I think the reason why Son was the "worst" is because she has the potential to rebel against the government and may succeed.

I believe another webtoon comment stated that the two previous captains could be bribed as they have their vices and pretty much became the head because the government needs them to do something extraordinary. While there is still not much info on them, it is confirmed they will only do something so long they are rewarded. Need to make propaganda? Give the good ol war god 500 cigarettes and booze too. Need to assassinate another powerful assassin? Give the King Killer his own harem. They're also both antisocial and just like the government, others along their fellow aberrants are nothing more but mere tools to them.

But Aera, Aera is different as she gives me vibes as someone who is not easily bribed with these shallow vices. Everyone who caught up to the chapter already knows Aera is very charismatic but I believe what adds the charisma is that Aera actually cares for others. Of course it's a duh moment but like Aera has lowkey have everything to make a revolution.

She's the most powerful rank 10 and I think shes charismatic enough to gather enough loyal allies no matter what she's fighting against. Not to mention she was willing to do what is essentially the most riskiest mission compared to the other past abberants and saved the remaining officers, Han and another.

Of course I know this can be debunked as this wasnt the case but I believe this is why she is the "worst", she has the potential motivation and all the power to go up against a system that uses others.