I'm thinking Charcoal is going to become a favorite of mine.
This was done for person on another website. The reference photo was small and did not show details and was in an indoor arena. So the face of the horse and rider were rather non-exisitant! The photo and drawing itself were too small for details in the bridle and saddle. I figured out very small details is very hard without having to sharpen the charcoal every time it touches paper.
Pretty happy with it though.