I think, deep in her heart and soul, she's not evil, she didn't know they sent her to exterminate(and probably kill her/let her die in there, idk, seems fishy what happened...i feel like the puppet master who did this knew Riven was different than others Noxians, such as Darius, and she could turn against them soon, so to prevent any troubles from her, they did it before it happened) and no to reform Ionia, but she seems to like battling with someone strong for glory, sounds a bit like Garen
If you listen to what she says, she doesn't sound like an evil person, "So much death.", "For those who were lost.", "To serve the greater good." , "My hands are stained.", she does like Noxus, but the methods they used...she doesn't approve them
"She carried out the orders of her superiors, terminating the remnants of a beaten and fractured enemy with extreme prejudice."
Riven shouldn't have done this and i think she knows it, I wish she wouldn't have done it, so that could be the reason why Singed bombed them, but it wasn't like that
So i think she has a mix of evil and good, but she seems to go to the good zone
"Once a leader in the warhosts of Noxus, Riven is an expatriate in a land she previously tried to conquer."
She's living in Ionia, alone? Yasuo? Can't wait to hear more from her

BTW, i hope Riot updates her lore and classic skin soon + cinematic about what happened to see HOW it happened and what is she doing after the exile
Oh and i can't vote, i click on Vote and the page just reloads