Tali (worst plot development, boring design, annoying dialogue, sole redeeming factor is the increased closeness with Rachael which is appreciated but it's still tainted by being Tali-related) and Natalie (don't like her at all, fills the same niche of "girl next door" as Stacy but was made purely as a roadblock to Harper, sole redeeming factor is oyakodon angle and even then I'd rather just have Harper)
On the reverse angle, I'd like to know from you people in this thread; Which 2 love interests would you like to take a more central role? Get "promoted" to "main girl", as it were. For me, it's Katie (love her dynamic with MC, she might still be evil and the idea of converting an evil girl through love/sex is hot) and Purple (love her visual design and she seems like an ice queen, which leads into "melt the ice queen", my favorite trope)