Well, just so there's no confusion about it I'm a straight girl. I just employ a large number of lesbians.
I'm more into realism than fantasy so the closer a character is to my own life experience the more I can relate to her. When you ask who is the best girl I don't know if you mean by looks (subjective) or by personality (also subjective). I mean I guess if I were a guy I would be interested in each one for different reasons, but obviously some more than others.
Sage is probably the most grounded character. Yes, there was the Chad thing but she's got the least baggage. Bella is probably the most interesting character of the known LI. What really is the back story with James? Jill will probably turn out to be a hard choice in a future episode (maybe this one, Episode 7) but as of now she's just kind of there. I reserve judgment on her.
Maya and Josy are the two that really make little sense to me. I get that the MC was attracted to Josy in the beginning but she wasn't exactly honest with him (lie of omission) and when he found out that should have been the end of it. When he found out it was Maya that should have been the end of her. Lies should end a relationship. Liars lie. It's not a one-time thing. It's a habit.
There are other characters I would like to see get more potential as LI but it's not going to happen. Nothing's going to happen with Jade beyond casual sex. Stephen is already an adulterer and she was screaming at him about it but she's one, too. Cathy could have been a LI but DPC chose not to go in that direction.
I think almost everyone agrees Quinn and Riona should have been LI but it seems they've been relegated to side chick status. Nicole is one that could have been a LI but that's not happening either. That one is going to come to an abrupt ending of some type.
I guess if I had to choose one LI over the others I would go with ...
only because I think she is going to have the most interesting story when all is said and done.