Krita is vastly better if you come to it from photoshop.
I doubt there is anything that couldn't be done in either and it is simply a matter of time spent in the UI and personal preference.
A lot more design oriented people are familiar with Photoshop or Photoshop inspired software so not optimizing for that is ignoring the vast majority of the expected target audience. And I doubt Gimp has the usability studies to prove their workflows are superior.