Different have different advantages, so I switch between them as needed. For 2D graphics, I primarily use GIMP, Photoshop, SnagIt, and occasionally IrfanView. For simple photo tuning, I use Picasa.
I've just learned to make new brushes in GIMP and Photoshop. It's important to realize that the brushes do not work the same way.
In Photoshop, the brushes are monochrome and take on the selected foreground color. The current version of GIMP can use Photoshop brushes without conversion.
Native-mode GIMP brushes, on the other hand, support multicolor images. If you don't select a foreground color after you've selected the brush, GIMP will use the colors in the brush image.
Today, I've been putting up various brushes and patterns in each format, in separate .zip file downloads.
Everything is completely free, no strings attached. Try them out if you like, and feel free to get back to me with your comments and suggestions so that I can improve.
Listening to: http://ancientfaith.com/