If you're on OS X...
...then Affinity show you just what a powerhouse closed source can be (I'm going to get *so* many downvotes for this) and just how good software really can be when it targets carefully, and integrates deeply with a specific operating system.
https://affinity.serif.com
As for "I haven't found anything in Photoshop that Gimp can't do", try > 8bpc images. Unless you're on the 2.9 beta, Gimp *still* can't do deep colour after years and years of waiting.
Biting the hand that feeds IT
