Though my favorite UX (and features) of all time is Paint Shop Pro 7 which i find superior to Krita (i have it installed alongside Krita, GIMP and Kolourpaint -used for minor edits since it starts instantly- on my Linux setup via Wine). I used it since Win3.x days in the 90s until PSP8 was released and they screwed up the UI. I moved to GIMP some time later when i started using Linux and used that for years. Some years ago i found a boxed copy of PSP7 anniversary edition, reinstalled it and despite not using it for more than a decade i found it much easier than GIMP and i'm using that since, until i wanted to make a plugin to assist me with texture painting for 3D models. Making plugins for PSP7 was very cumbersome so i thought to try Krita instead (Krita has an MDI mode which i like when working with images) and ended up sticking with it since making the plugin was relatively easy[0].
I'll download Krita's source code and try to build it and add the features i miss from PSP7 at some point, KDE people do not seem very allergic to having options so i might be able to recreate the stuff and behavior i miss from PSP7 in Krita.
In order of preference:
1. PSP7
2. Krita
3. Pixelmator (only under macOS of course and i only used an old version before App Store with the only alternative being GIMP running under XQuartz - i think GIMP got a native version later but i never used it)
4. GIMP (i found older versions easier to use, but every time they introduce a new major UI change i find it more awkward than before and now they're switching away from Gtk2 to Gtk3 -which i dislike the feel of- i decided to stick with Krita)
5?. Photoshop, maybe (i only used it a little in the past, always found it more cumbersome than GIMP or PSP, but it'll do if nothing else is available)
