The answer to the question of which is best for powering a scooter or motorcycle depends on several factors, such as:

Performance: A chain drive often delivers more power and performance than a belt drive or shaft drive.
Maintenance: A chain drive requires more maintenance than a belt drive or shaft drive.
Reliability: A belt drive and shaft drive tend to be more reliable than a chain drive, but a chain drive is less likely to break than a belt.
Noise: A chain drive is often noisier than a belt drive or shaft drive.
Price: A belt drive and shaft drive are often cheaper to buy and maintain than a chain drive.
The best for your vehicle depends on your personal preference, budget and use of the scooter. Consult with an expert and consider all factors before making your choice.