Are you a new or an experienced scrum master looking to either have your knowledge formally recognized or simply have a certification to improve your chances with your next job?
You then have the following 3 choices to choose from
- Certified ScrumMaster® (CSM) from Scrum Alliance
- PMI Agile Certified Practitioner (PMI-ACP)® from PMI
- Professional Scrum Master (PSM) I and II assessments from Scrum.org
CSM is the most recognized followed by PMI-ACP but PSM has started to gain more acceptance owing to its lack of requirement for mandatory training which, in my opinion, is a waste of your hard earned money especially if you are an experienced scrum master.
If you have your company sponsoring the training, then I would recommend taking either CSM or PMI-ACP else I would recommend PSM I which you should be able to get in 3 weeks if you work hard and practice a lot.