I'm going with Gianna, and here's my rationale;
Ava, while she's a dirty slut and does anything and everything, ruined herself with her breast reduction, not because of size, but because they look like crap now.
Sara Jay does have the curves, but her face is too manly for me.
Gianna is young, energetic, has great tits & ass. Tittyfucking her would be a pleasure.