I’d go for the original, because honestly, I don’t even really know the rest.
I never played CCC, so I don’t know anything about Passionlip or Melt. BB is just straight up annoying in all of her forms, while Parvati is just lacking an identity. Kama and Kingprotea aren’t in the game yet, while the last two pretty much only exist as references and design-material. That leaves literally nothing but the original, and as far as I’m concerned, she is the canon heroine of the VN (though I think the whole extended Shirou-harem with her, Rin, Seiba, and Medusa is also pretty fun, but a bit excessive).