I am a professional designer with two decades of experience and I gotta admit, you're smoking crack if you think GIMP (the project that is almost entirely held back by its stupid name) is superior to Photoshop.

It might be able to get the job done for small tasks, but it is not a serious tool for serious people. I'm sorry. I'm as pro-FLOSS as anyone can get, and even I recognize that right now there's just no competition in the design department. Affinity is Mac-only, and comes with its own problematic aspects.