Although Krita is well known as an artist’s choice, it and GIMP aren’t as far apart as you might think when used for art. GIMP features the essential tools such as paintbrush, pencil, airbrush and ink tools, along with the expected plain, gradient and texture fills.
In addition to the expected bitmap-based drawing features, Krita also has vector drawing facilities, and although it wouldn’t be a match for a dedicated vector drawing program like Inkscape, in that department the features are surprisingly extensive. GIMP also has some vector drawing facilities, which are welcome, but they’re not quite on the same level as those of Krita.