Rhea is an easy pick. She’s young and unique in look and presentation
If Bianca fails that’s on the company not her, everything about her screams star.
Toni Storm can be female 2019 champ Kofi
There's really zero reason for Bianca not to be a superstar. Not only is she over with wrestling fans, they did a focus group of non wrestling fans and Bianca ranked the higher than both Bayley and Charlotte.
Who Are WWE's Next Megastars? Non-Wrestling Fans Predict the Future
I think there's actually a decent amount of women who could be credible champs without needing super creative booking, but some of them are injured: Mickie James is still one of the best workers in the company, Ruby Riott can go, Ember is legit and mad over with the crowd. I'd also say, as much as folks dislike her, Nia could be moved into the title picture the minute she returns and it wouldn't look out of place. I'm not an Alexa fan and her ring work is passable at best, but she has the kayfabe record to be in there (never forget getting run over by the Bliss bus and sacrificed for her is what damaged both Becky and Bayley to the point where it took years for them to recover and get back to the top and she does have a title win over Sasha. Yes, I'm bitter and biased lol).
Given good booking and a solid build, Naomi, Sonya, Nikki Cross, and Mandy could get a title put on them and it would be believable.
NXT has a legit pool of talent to pull from too. Besides Bianca, there's Mia, Rhea, Shayna, Io, Toni Storm...any of them could do it without needing booking shenanigans. With booking shenanigans/a good build I'd argue that Dakota Kai and Tegan Nox could be in the mix as well.