I see - I need to elaborate. An ideal editor would be intuitive and have a simple layout. Without having ever used the editor before, I should be able to just open it and get how it works and be able to do whatever I want.
Keynote is pretty good at that. The unintuitive part is how to get your edited image out of the program (I have an Apple script that I wrote just for handling taking the currently selected objects in Keynote and exporting it as a png with a transparent background.) Cropping can also be pretty tricky.
Photoshop is not that. I open it up and I have no idea what I'm doing. Same thing in GIMP. Photoshop / GIMP are nowhere near that - I can't do anything in either program without extensive googling and manual reading.