What are we thinking? Three extremely successful pop princesses, they all seem like ESFP's to me. But when you listen to them in interviews they come across more introverted, especially Britney and Beyonce.
I was really suprised to see how humble that girl is considering the performance/ persona she has on stage. I would say for both Beyonce and Britney ISFP, although Britney has her wild 'extroverted' moments whenever she starts drinking. Then Rihanna seems pretty loud and outgoing in real life so I would put her ESFP.