Aboleths are by far the most amoral of all the Nations in the game. I don't care what anybody else has to say about it, it's a fact
Above and beyond R'lyeh, Ermor, Mictlan, etc, Aboleths are a bunch of seriously cold bastiches.
Infact, morally speaking, in terms of sacrifice for the common good, and the way those sacrifices were historically treated (as sacred royalty, for a whole year), Mictlan might actually have the moral high ground, in the game, if we can assume that the same historical practices were going on, behind the scenes.
Ofcourse, they aren't *our* set of beliefs and morals.
And I don't find Marignon particularly good. Too oppressive, and too fanatical about maintaining that status-quo, to the detriment of their own people. Torturing and killing their own people over religious issues, and creating an environment of terror, isn't moral, no matter what they might represent.
Pythium, although you can speculate that they're religiously tolerant, isn't a lot better, since you'll note that they pit gladiators against hydras in their arenas, for mass entertainment purposes.
I've never thought of C'tis as having a particular moral status, but if they do, I'd guess it would lean towards good, since ancient Egyptians did everything they could to maintain and expand their society, to the benefit of their citizens. There was, ofcourse, a great division between the Haves and the Have Nots, but the people most empowered, the Pharaohs, were expected to dedicate their entire afterlife-the central theme of Egyptian culture-to defending the world against demons and destruction. They did ofcourse have slaves, but those slaves could themselves rise to high position, based on their abilities.
I can't think of a deciding factor for Arco, but it would probably depend on how well they treat their elephants--their greatest war asset. Considering ancient Greek society, I'd say Neutral. They had a lot of good things going on, and a lot of bad things. They definitely *did* have slaves, and the Spartans atleast treated them horrendously.
If we consider Late Age Ermor, you won't find a more democratic society in Dominions. Everyone becomes a lot more equal, once their dead. No racism, no torture or slaughter of their own kind, no religious intolerance, and they don't even blood-hunt, and they want to spread the benefits of their society to everyone--and their *are* benefits to being undead-to their neighbors.
Late Era R'lyeh is pretty evil, but they're evil because they're insane. It's not cold calculation, it's misguided fanaticism, perhaps brought on by desperation, considering that the Illithids *are* lost aliens trapped on the surface of the Dominions world. They're not E.T., but they're not Predators, either.