Which is better scrum master or PRINCE2 Agile?

Whether certification as a Scrum Master or PRINCE2 Agile certification is better depends upon the purpose you are seeking to fulfill. If your purpose is to get a job working with an agile team as a Scrum Master then you should take a Scrum Master course and seek certification. If you want to learn a project management method that you can apply on agile projects then you should take a PRINCE2 Agile training course and seek PRINCE2 Agile certification either at Foundation or Practitioner level.