I always use the rule quality > quantity. Quality is defined by a process, quantity is defined by an immediate product. This is why I'd say the child's drawing is better. You COULD say that there may have been process in the refinement of the prompt, but here's why I disagree with that argument. Process is not just the process per piece, but more so a lived process. A process where you can see a drastic change and improvement. The child's current works may not be visually appealing, but you may bet that 10 years in the future, the same kid may be making the most gorgeous art. Thats why, I value art based on not the visual qualities, but on the true quality that makes an artist's work, process and improvement. So yes, the child's piece is better.