Lately I've been mostly using my iPad with a couple drawing programs I got for it. Porcreate is a very versatile program that has me working in "oils", "pastel", "pencil" and "chalks". I have found myself sketching in this program more than in my sketchbook. The other program that I've been using is Art Rage which I find has a better set of watercolor functions than the Procreate. The painting brushes are pretty good too but my main complaint about this program is that it's cumbersome to adjust the qualities of the brushes and I prefer the sliders in the Procreate program.
Below are a couple trial sketches with each application. Try them out for yourself and tell me what you think.
Sketch using Procreate for a monotype
Watercolor trial using Art Rage