What I miss most about painting digitally is the rich, textured look of oils. So I've tried for years to achieve that look in Photoshop and Painter with all the various brushes, filters and settings they have. Finally, I stumbled upon the brushes with the little drip icon on top of it (oil, pastel, airbrush, etc). It's not quite just like painting in oils yet. But with practice, hopefully, I may never miss oils again.