Ariana, Selena, Demi, and Katy all feel the most contrived, non-risky and obvious in their pandering for commercial success.
Ellie is also doing the manufactured, paint-by-numbers Max Martin thing lately. It's sad because Lights showed so much promise.
Rihanna used to be obviously manufactured, but she seems like she at least wants to break out of that cycle. Even if I'm not really feeling the singles she's released this year I respect that she's trying.