Pan after a long fight.
Since Akira Toriyama never demonstrated that female human/Saiyan hybrids go into Super Saiyan state (I think he said he didn't knew how to draw a female super saiyan), Pan would lose to Frieza. Frieza was bested by Super Saiyans and folks who are on par or above Super Saiyan level. I could be wrong since I'm not a battle person. I'm just an observer.
This is an interesting match-up.