I use mainly photoshop... I have OpenCanvas but it confuses me with its brushes.

I think my favorite art program so far is SAI Paint Tool, but my trial for it ran out. ;___; It was the prettiest program everrrr--everything was so organized and user-friendly, and the lines came out so crisp and smooth so it was excellent for lineart. Its waterbrush tool was also really great for blending colors. I miss SAI. Dx