The best criterion for evaluating a piece of art can depend on the specific goals and intentions of the artwork, but if we consider a general approach, "use of color to emphasize a particular area of the drawing" is often a strong criterion. This is because color plays a crucial role in art, influencing mood and focus, and can be fundamental to the artist's expression and communication.
However, if the piece aims for realism, "technical skill to create photorealistic imagery" could also be a valid criterion. Ultimately, the best criterion will depend on the context and the specific work being evaluated.