These are the factors I focused on while judging:
Novelty/Originality -- If the song was completely original and variable (not repetitive).
Orchestration -- If multiple orchestral instruments were used, and if instrumentation was of a large scope.
Emotion -- If the song contained movements that affected strong feelings.
Realism -- If the instrumentation was realistic, or performed/sequenced realistically.
Composition/Arrangement -- If the song was well structured and intricately defined. Spending more time on your song would have helped this score.
You all can compare your scored with the list above.