Moving from pop-country into Max Martin pop was such a RISKY move
Lets be honest she was never country. Apart from Our Song she doesn't have any country songs. The rest is at least 90% pop with a sprinkle of banjo to make it a little crossover. She moved to the safest producer in the industry. Like her teenage girl catering music wasn't safe enough prior to that.
Now Katy... hmm. Super safe as well...
Can't really pick tbh. Probably Taylor though, cause there's no diversity in her songs. She only writes about people who did her wrong.