My favourite photo / image editors are : imagemagick, and shotwell… mostly I’m just cropping screenshots anyway, shotwell is more than adequate…
I do occasionally indulge in a bit of sketching / doodling - I scan line/ink/pencil drawings on my MFC, then use imagemagick to subtract all the non “dark” pixels and save as a png file with transparency, then import those into my drawing app (either Autodesk Sketchbook on Android and iOS, or Procreate on iOS [iPad]).
Don’t find myself using GIMP very often these days, what I kinda HATE (i.e. it peeves me!) about GIMP is its insistence on saving in its native file format, most times I just wanna open a jpg or png and edit it and save it - and never bother with XCF file format…