I too am very interested in Dominique/Junko+Kiyomi as poly-LI's to my sweet Olivia. Claudia is also very tempting as she's not overly corrupted and sadistic as her sister Celeste and its not too late to sway her to the light. I also agree that Sam is indeed a hot mess but too extreme to be redeemable for me. If I'm willing to fool around with morally gray/questionable characters, I like Patricia, Phoebe, Elena, Veronica and Delilah=Chanel for me, which is to say I'm down to have fun as their superior and Dom them, without looking to romance them.
I initially liked Alessandra, but she's second to Juliette is terms of cruelty and sadism, only she hides it very well behind a convenient mask of innocence when around Olivia. Additionally it sounds or is inferred she prefers the company of women over men, so I don't think we'd get a real romantic path with her even if she was able to be redeemed.