Paint.net is pretty notable too. Windows only, but free, and halfway between paint and what Adobe offers. There are many plugins that either meet or exceed what you can find for Photoshop.

Both Pinta and Krita had really weird interactions with my touch screen the last time I tried. GIMP was the only one who worked correctly - I presume because it just treated it as a mouse (it may well be that my Linux configuration is to blame, not Pinta and Krita)

Perhaps things work better now.

Yeah, I think Pinta could be considered as MS Paint++ for Linux.

I use kolour paint. Don't really do much outside of resizing and cropping though.

Seconding. I'm pretty happy with KolourPaint, but all I use it for is resizing, cropping, and blocking out people's names and pictures in social media screenshots.