Gianna, for sure. Sara Jay has what is probably the ugliest face in porn; no offense to her, it's just my opinion. Ava Devine is 98% plastic, which is a huge turn off for me. Plus, I don't like her dirty mouth; hearing her call herself a "dirty fucking slut who wants her asshole stretched wide open" makes my dick drop like lead.
Gianna on the other hand is 100% natural and although she does have some colorful language, generally it is not misogynistic or abusive. The great thing about Gianna is she knows how good she is at fucking and exerts her power over her partner.