A couple months ago, I had to create some annotated screen shots to be used as cheat sheets by a number of people I'm working with. I knew that I could do something like this in Photoshop, having used Photoshop a bit 10 years ago.
I first tried GIMP, because it was free and available. After trying for a while to figure out how to get layers happening, I finally gave up and downloaded a copy of Photoshop. Everything was immediately intuitive. Even though the Photoshop UI had changed (a lot) from when I had used it a decade ago, I was able to very quickly create my annotated screen shots.
Now, you could say that I didn't bother to read any of the GIMP documentation, and you'd be right. But with Photoshop I didn't have to.
But I don't know if Photoshop would be nicer in that regard , I haven't used that in a long time.
I started with Paint Shop Pro, and what it lacked in features it made up in ease-of-use. I especially liked the ability to mix raster and vector layers; Photoshop still hasn't captured the simplicity and power of PSP's vector layers, IMO (in terms of UI, at least). After I used PSP, I moved on to Photoshop. While it was initially a bit intimidating, my familiarity with PSP quickly helped me overcome this and I was up to speed pretty fast. Fast forward a long time and I try Corel Painter. Its interface is definitely different, but still easy to follow. I picked it up in a few minutes (for some definition of 'picked up').
Then I tried GIMP. I couldn't make heads or tails of it, and I never got used to it. I can't explain why GIMP doesn't work for me; just that I didn't -- couldn't -- pick it up like I did Photoshop or Painter (or openCanvas for that matter).
I used Corel Photo-Paint for years and years, and when I tried Photoshop after that, it seemed like it was designed by space aliens. I don't mean to say that Photo-Paint is easier to use -- I doubt it is. But when you get used to a particular interface for something like photo editing, maybe any given interface is ok, but switching interfaces is hard?