This article makes sense, Britney was more like Janet as an artist, and Christina was the one more like Madonna artistically. But because Christina had a voice and also did R&B, she was seen as more of a Mariah type artist. And I guess Janet isn't as high profile as Madonna and Britney also had VMA stunts and got media attention like Madonna
I don't think it's a racial thing though because Justin Timberlake (Katy Perry too

) was seen as the new MJ and he's white of course.