I finally got around to reading the serialized version, up to the latest chapter (18). Read the original as it came out and wanted to reread it real quick before starting this one, to remind myself where it stopped. I felt like the original had a better flow with its story beats. The reveal that Fuu knew about them being succubi and Yukiko not remembering showing Fuu her true form and Yukiko/Konomi developing a non energy based relationship felt more natural in the original. Although, I'm glad the love triangle still seems pretty 50/50 (or at worst 60/40). At its core it's just a childhood friend vs new attractive person triangle, but I think the succubus dynamics each has really make both pairs feel unique.
As a sucker for childhood friend pairs, I'm glad Fuu seems to be the more likely choice, in the serialization. Even in the original when she had a bit of a villainous tone to her actions and dialogue, I was still kind of rooting for her. I like the Konomi route, about succubi loving each other despite only viewing sex as a means of survival. Especially, with how much of an emphasis they put on NEEDING humans for energy. But, Yukiko relating to Fuu about feeling like an outcast and sharing her own alienating secret, Fuu's interest in (wo)man eating predators, like sharks, and also thinking Yukiko's succubus form is still pretty, and both of them still wanting to be more to each other than just food/energy. I just think they have more love with each other. But, I'd still be cool with Yukiko/Konomi or more so a poly ending(especially if this was the original).