Or even Inkscape for Illustrators if you're planning on ditching the Adobe blood-sucking machine. The fact that you can even mention it while leaving out a great app such as Pixelmator/Pixelmator Pro shows a lack of hands on research. GIMP is just outright crappy, unless you like the feel of UNIX X Window system built apps or old style Windows Apps. It's usually my go to when getting any of my artist buddy's in to the fold. ProCreate is a great app for sure, and especially for the price and feel for a traditionally trained artist.
