Well, I guess it's my turn to explain my choices regarding the tier list.
Gardon: Gardon is the ONLY human in this story, who is willing to do what it takes to defeat the demons. Sure, he is not the purest, most honorable guy, but he gets the job done, and has good intentions. I think Gardon is how Nietzsche imagined the Übermensch (at least in my opinion). Think about it. Gardon lives by his own moral code, does not yield to anyone, is willing to walk the walk, is very down to earth, and most importantly, doesn't let his ego go to his head. (He is confident but never overconfident.) He has been tutored by Brian, but unlike Amari, he never became his puppet. (That's why Amari is in A tier instead of S.) It wasn't Brians teachings that made Gardon who he is now. Yes, Brian influenced Gardon, but Gardon was always a "hero", one who was willing to wage war to save others. One might argue that he is not the savior, but the slaver of humanity, but I'd say he is more like a Dark Messiah, a visionary who made the world around him crumble, and built a stronger nation on it's ashes. Of course I'm not saying he is a "good" man, he is far from that... how do I put this... if I'd have to sum up Gardon in a sentence, I'd say he isn't the hero Arkain deserved, but the one it needed.
Larine: The supreme waifu. She can heal you, is very sneaky, has a friendly hawk, and can create illusions. But seriously, she is such an underrated character. Her lover was propably killed by Renova, she got exiled, her people hated her for telling the truth, then found a like minded person, with whom she could finally experience everything she wanted. Gardon gave her a home by his side, they had children together, and he was a loving dad, as much as she was a loving mother. I'm a big Garine shipper, and wish they had more dialouge, because they deserve it. To ne their love is the most moving thing in the entire story. Also the ring had nothing to do with her affection towards Gardon, in Death of a Legend in the SHB she already greeted Gardon with "What can I do for you Gardon?", before he did anything to her ring. I ship them so much, I hope they get more screen time... ahem... back to Larine: An elven girl who knows what it's like to be a homeless exile, she'll make a perfect queen because she wasn't born to be a queen, she will understand her subjects because she is one of them, unlike Renova.
Brian: Oh man... Brian is one of the four, and in my opinion, the smartest of them. Let's see, he never tries to do things for a stupid ideal, or petty revenge even though he got the short end of the stick back when Aridon decided that he wanted to uphold his "balance". Brian is a pragmatic person, who never does things out of zeal. Cold, calculating but ultimately... well intentioned. Yes, you have heard me right. Brian is a well intentioned person. He doesn't consider himself a god, (even though he kind of is) and wishes to help the humans and orcs. He's helping the younger races of Arkain, because Brian realises that change is the constant. The world will not stop, and you have to give younger races a chance too! The humans and orcs are both worthy of the world, and Brian knows that. Unlike Aridon he is not self absorbed, has good manners, and he tutored Gardon and Amari, to help their kind. Without him, the orcs would have died under the idiotic leadership of Rangul and Rath, and that is cause enough for me to rank him above his brothers.
Pentiss: I like her because she brought something to the undead story, that makes it much more interesting. Intrique. She isn't a slave of Aridon, she has her own will, her own agenda. She seems like a loyal servant, but I think she is the going to betray him, if the war doesn't go the way he has planned. She's smart, very entartaining, and most importantly, still alive. Pentiss is a wild card, and I'm waiting for more black lotus shenanigans with her. She recognized that Gardon is very strong, while the other undead leaders didn't. (Yes she wanted to torture him, but that's besides the pont

) In a way, I think Pentiss is like a female Petyr Baelish form Game of Thrones, with a bdsm drug fetish, and that alone is reason enough for me to put her in S tier.
Vanessa: A well intentioned girl, who wanted to change the orcs to be better. Unfortunately Rangul and Rath were stuck in the past, and wanted nothing more than pillage and murder. The sisterly bond between her and Amari is cute (even though it feels like Amari is just using her), and she has a vital role in the creation of the Tribal Dominion. She proved to the orcs, that even a human can meet their standards, without becoming a monster like Rath. She is brave but not foolish, good but not soft hearted. Even without proper parents, even after suffering a trauma in her childhood, even after everything... she is still a nice person, who wants to do good, which is why she deserves the S tier. The only problem with her is that because of her good nature, she isn't willing to do what it takes, (unlike Amari and Gardon) and it hold her back from making a difference, which is why I almost put her in A tier.
Borean: To quote nchp1903:
He's a talking, dancing, rolling bear in one damn package. It's endearing, it's beautiful. Call me a furry if you want, but honestly, I just want to hug him.
There is not much else to say. He is THE best character in Arkain. He doesn't deserve the S tier, the S tier deserves him!
I'm going to skip a few tiers because explaining everyone would take way too long.
Edoarus: Psyco death knight. He is not that interesting, has basically no independent thoughts, and is a slave to the Watchers will. F tier it is.
Retka: Idiot. Got played by Van Durce and the "Emperor", couldn't even conquer Toran, his soldiers weren't loyal to him (because he was a power hungry bastard), he allied himself with thiefs and bandits, and sent poorly equiped conscripts to their death, just to slow Gardon down, and in general he seemed like a prick (he didn't even value his own sisters advice, because he was so overconfident in his own none existant abilities). He would have made an awful king, so F tier.
Rath: A genocidal maniac, who thinks killing innocent humans will somehow fill the aching hole inside his heart. Revenge never brings satisfaction, and 90% of the humans Rath slaughtered had nothing to do with what happened to his clan. He only fuels the never ending conflict between the two races. He also sacrificed his warriors for nothing. He truly is the worst chieftan.
Genethas: This guy. Ebira made him her puppet, and he's even proud of it. He is stupid beyond comprehension. The only reason he succeded, was that Blen is a blind fool. Genethas is a spinless traitor, a tool of the demons, he belongs in the F tier.
Meya: Same as Edoarus, only worse, because she has a disturbing necrophilia paired with an unhealthy vanity.
Fleshtearer: Who is he? Oh yeah, the... thing that doesn't have a single dialouge in the entire story. I wouldn't even put him on the tier list, because he is not really a character, more like a moving prop.
Bonelords: Oh great, more genocidal maniacs, who want nothing else than to kill... wait everyone? They are on a crusade against flesh?! Yeah, the Bonelords aren't that complicated. They look cool, but that's it. Aridon wouldn't let them kill everyone anyway, so they are just... F tier.
Aridon: I hate Aridon. He wants to uphold some kind of "balance", but in reality, his actions just cause even more conflict. He has a literal slave army, and he is not afraid to use it. If he doesn't like what you are doing, he is going to come after you. Because Aridon is a paranoid control freak, with an obession. Balance. Aridon likes to rob people of their free will, and then make them do things they don't want to do (Saphira and Mordin). He is a self righteous, self absorbed, backstabbing lunatic, that think the world is better off with him pulling the strings. He calls himself the protector of Arkain, however, in reality, his actions show that he doesn't care about Arkain, or it's various races. He is deluded and his machinations all serve a pointless purpose. I think Aridon is the true villain of Legends of Arkain, a creature that must be stopped, no matter the cost. F tier.
The Sas tier. Weirdly enough, I didn't put Sas in here, because, (even though I heavly dislike him) he is just an idiot. These two however...
Redfist: He hates the orcs, because they killed his family. Now he is angry. That's it. He is a completely unlikable monster, who is (in my opinion) not a tyrant, but a raging 3 year old. He made the Redfist faction to combat the orcs and in his twisted view "help" humans, but when he actually gets her long lost daughter back, who has been "brainwashed" by the orcs, he doesn't even attempt to reconnect with her. If she joins his side, he just kills her for no reason. He has an understandable backstory, but he is an awful human being.
Rangul: Rangul is a different case. He wants to raid the human lands, and that is understandable. He is a simple minded greenskin, who wants to pillage in the name of his twisted idea of "helping orc kind". That is not why I hate him. Amari wants to help her kind as well. The difference between them is their methods. Metaphorically, if Amari and Rangul are freezing on a cold night, Amari will make a campfire to keep herself warm, Rangul will burn a village, and in the process, accidentally kill himself for good measure. What did Rangul achieve in the end? He left the orc islands unguarded, and thus, robbed his people and himself of a place they can call home. He helped the demons break through the front lines, weakened the humans and their allies, made Rath, an unhinged psychopath, the leader of the Darkmind Clan, and favored Sasrogarn the idiot, instead of Amari. He also lost control of the entire situation once the demons broke through the human front. The entirety of his race got endangered, because he wasn't as smart, as he thought himself to be.
In my opinion these two deserve each other. Two short sighted old man, slaughtering each others race, because they are too stupid to realise what the real threat is. (The demons and the undead.)