Beyoncé >>>
Beyoncé's voice has grown as she's grown, she's sung about everything in the book, including sex, and she's sung about it from multiple perspectives, as a girl, as a young woman, as a married wife and mother, there's nothing in the current era of popgirls that can beat her in that department, and it's honestly way preferable to Britney's voice as far as sex appeal goes, because Britney's been using the same baby talk singing voice to mask for her own lack of versatility to the point where she uses auto-tune and flat out gets other people to sing on her latest album to mask the fact that she's a grown adult and can't pull the innocence + sex appeal that worked for audiences when BOMT was released.
#MyThoughtsOnTheMatter
I don't know what it is about Beyoncé, but when she tries to do ****ty sexy, she just comes off as a cheap street corner hooker, whereas Britney has that mysterious alluring quality about her voice when she "does the dirty". It's hard to describe, but Beyoncé's image has been built on more of a strong woman image, whereas Britney has always had the sexual undertones from the start. It seems more believable when Britney does it.