Drawings - my 2 cents worth.
I think 3D Poser-like software is OK for people who want to visualize their own fantasies. But I usually find the results of such 'art' (however skilful) to be incredibly stiff-limbed, awkward, and lacking in the relevant kind of detail!
It is my custom to ornate all the stories I keep with art (at least one cover picture, sometimes much more). I never use photos or fakes for many reasons, and hardly ever use computer art. The old-fashioned artists - from Dolcett to Pichard - are much better: elegance, clarity, naughtiness, and the freedom to show things that would blow the tops off censors if shown in photos!
I cited elegance first - and that was not due to chance. It should be a prerequisite!