And that's why for me Luna is the best and far more interesting character of this game.
There's a good reason for that.
The missions for Gracie & Isabel have not involved a traumatic flashback that form an emotional bond as strong as the one with Luna.
Isabel has some emotional trauma over her relationship with Antonio, but nothing as heart wrenching as her being kidnapped, imprisoned, tortured and abused as a child.
Gracie clearly had something happen, which has made her so disassociated from other people. Whatever happened in the forest is what most suspect to be her traumatic event.
Whatever happened to her, it's still not likely to be more horrible than what happened to Luna.
As a result, Luna's the one with the strongest emotional bond & you opinion of her is largely shared & probably intended.
I like them all, for different reasons, but will reserve judgement on which character is best, or most interesting, until we've seen their full stories.
I can say that Luna's is the most interesting for now, with the story we have had so far, absolutely.
But most interesting generically cannot be said with any veracity, until all character development arcs conclude.