Many years ago I spent quite some time getting used to Gimp and did some designing on it, etc. I also wrote a tutorial for it to create some torn paper effect.

I say all this to give some context to the following: GIMP is just not great software. It is super unintuitive and when you don't use it for a while, you totally forget how to use it to select things, put them on layers, etc.

I use Pixelmator on Mac. I bought it years ago and haven't regretted it. It is getting better and better of the years, the UI is great. When I use linux I miss Pixelmator more than I do Photoshop. So if someone were to create a Pixelmator-inspired editor for linux, that would be great.