I too have tried to use GIMP over the years. GIMP can be good for some things, and can even be great for a subset of things, but the overall workflow is very convoluted and difficult. I seem to be trying to do things in spite of the program.
I know there are some people who do great things with GIMP, and I have sung the praises of specific features (they had a resynthesize before Photoshop for example) but overall, Photoshop, with all its warts (and there are many) is just more cohesive.
Back on topic, I have never really been able to get much out of Krita. I am a photographer and quite tech savvy, but I do not "get:" Krita. Maybe I will have to try again...