Taylor is great, tho overrated. Beyonce is pretty good in terms of talent. Adele obviously, she's the "OMG WOW! THE VOICE!!" one they need to avoid the obesity.
Rihanna is kind of forgettable, she relies on what type of image/sound she's currently hopping on.
Katy

She's a twerp. I can imagine her doing a GIANT, 4 month Claires "SPECIAL KATY PRODUCTS!" giveaway. Pink shoes, fairy wing costumes, and meow earrings with "KATY PERRY!" written in bright purple.