Well, i've read most of the topic and must confess, some statements were indeed funny. (especially the one concerning Bastila's and Atris' domination behind closed doors^^)
So here's my listing:
Juhani
Because I personally don't like women with fractures in their face...it would be like having a romance with Darth Sion. It also seems to me as if Juhani is quite unexperienced in romantic things, so despite her potential wildness, what remains? I disliked her in KotOR I and only allowed her to stay in my party because she had control over the force. She hasn't enough self-confidence to be interesting.
7) Visas
Well, that might be surprising, but it's the same problem which I have with Juhani. Visas is too devote to be interesting to anyone else than a sith lord. I also would like to see her eyes or what would be there instead of eyes.
6) Mission
As many of you said, I have a problem with the fact that Mission is only fourteen in KotOR I, even with nineteen I consider her to play the "little sister"-role instead of the partner role.
5) Atris
I must confess, I like the white hair of Atris and Brianna, but, as it was said before, she sounds a bit too old, even when you take into consideration that Mira tells you, your character was too old for her, from which i draw the conclusion that Atris and you must rather be at the same age. But behind closed doors she would say things like "You still haven't learned anything." and all the other stuff she is telling you on your first visit in the Academy. And I am deadly sure she would say: "I didn't know, your lightsaber is that small."
4) Yuthura
She is quite interesting though I personally like Twi'leks like Oola in ROTJ and Yuthura seems to be very skillfull and experienced. But you don't learn enough about her to take her honestly into consideration.
So here are the top 3
3) Bastila
She is the charakter which has the most lovely modelled body and head. She is the one with the most interesting movements of her hair. And I disagree with the statement she would correct you behind closed doors - at the end of KotOR I you have taken over the role of the master and she is the servant from then on. But Bastila seems also a bit too unexperienced and her moral conflicts could be a major problem at the wrong time.
2) Mira
Wild, self-confident, clever and respectless. She is the ultimate definition of the woman of Darth A.Donis' (my charakter, I don't know if the joke is understandable for non-Germans) dreams. I also like her red hair and her breasts for sure. But the little conversation options I had with her frustrated me, so I rank her only second.
So there's only one girl left...and, not very surprisingly, it's
1) Brianna
She has control over her feelings most of the time, she has white hair (I said something about that when I dealt with Atris) and she has a wonderful body. You should also consider what she could do with you with her techniques of the Echani. She is sometimes rational, what makes the whole thing much more interesting to me. So that's why Brianna is my favourite and I hope of a ROTH in KotOR III!
P.S. I hope my posting was at least partially understandable