Cersei is evil and cruel with flashes of humanity (that are all but gone at this point). Probably lawful evil. The Mountain is pure evil with a complete lack of humanity at this point. Ramsay was a sociopath (chaotic evil). Same for Joffrey and Euron. Arya is good with flashes of evil/darkness (chaotic good). Ned was lawful good. Jon and Dany are morally good. Brienne is both. Jaime straddles the line between good and bad (chaotic neutral?). Ditto for Stannis who was on the "right" side but did some truly awful shit (lawful neutral?). Tyrion is chaotic good. Tyrells are probably lawful neutral too. Martells are chaotic neutral. Yara and Theon probably chaotic good at this point.
I would not put Stannis as lawful neutral. He's been on the bad side of the spectrum for me ever since he prayed for Robb Stark to die. And then he tried to make an ally out of his half brother Jon. And then, of course, it was revealed that the quest for power was more important to him than his daughe's life, so he is a scum fuck.
Ned was lawfully good but he had other issues as a character; he was naive, stubborn, perhaps at sometimes even arrogant, same could be said for Robb.
That's what I learned after a rewatch on the series. The first time I watched the whole show, I rooted for the Starks 100% and thought they were all the victims. While most of that is true, they had some character flaws in themselves and weren't completely innocent.
Who does Cersei surround herself with? Qyburn who has a dark and sinister side to him and the Mountain who is clearly evil, just as much as Joffrey or Ramsay, he just didn't have the influence or intelligence to be quite as devious. Cersei is on the evil end of the spectrum. Didn't she have some friend of hers permanently disfigured over some petty squabble when she was a kid? I recall them talking about that. She was physically and verbally abusive to Tyrion even as a baby.
She doesn't need to be a psychopathic sadist in order to be evil, she is evil so was her father. She does desire power, she clearly loves playing the game even though she's terrible at it. I mean for her to be a grey character, she has to do something that's kind once in awhile doesn't she?
and she employs the Mountain in what seems to be her most loyal servant, and this thread establishes he's the most evil