Artrage is a fun program designed to mimic traditional media. It’s similar to Corel Painter except where the full version of Painter will run you $360, Artrage Studio Pro will only cost $60. Also the interface on Artrage is similar to Autodesk SketchBook Pro, which is easier to navigate than Painter’s. (Fun fact: if you like Sketchbook check out Sketchbook Express on the Mac App Store, iOS, or Android. Sketchbook Copic Edition might be worth checking out.)
Artrage is nice for giving digital art more of a loose and painterly feel and for easily blending colors. Here’s an example of inking clean lines in Illustrator and then painting the colors with Artrage.
It’s really easy and fun to get some nice impasto effects when painting and to work from references within the program.
The brushes are easily configured and customizable. It also comes with a selection of paper/canvas textures as well as letting you import your own.