This is sort of how I see things, but this is just my impression.
Rihanna - super chill, easy to get a long with, a little shady, but possibly just in good fun. I don't see her as catty as some of the others, as she probably just doesn't care. (but she has been rude to some fans, so not sure
)
Beyonce - she probably thinks shes superior than the rest, but still i see her as humble
Gaga - Well she is just a god sent angel, and I don't think I've heard one bad story about someone meeting her, she seems genuinely friendly to everyone
Taylor Swift/Katy Perry - catty, bitchy. extremely competitive. (katy tries to be sarcastically funny, but it just comes of as crude, and impolite) I could use other words to describe them but I CBA. I like their music, just don't care for them personally, and wouldn't bother to approach them