There are several essential factors that need to be carefully studied before enrolling for a course. Symbiosis is a better choice for sports management, being a more established and well-known institute. 

The points below are some key highlights as shared by my sister who has graduated from IISM: 

• The materials and overviews on the IISM official website are not quite satisfactory. It is somewhat similar to that of IIPM, having no specific stress on subjects and course outcomes.
• There are some big names on the advisory board of IISM, but it is not enough. It is important to consider whether IISM provides a recognized degree or not, which is the main required outcome of the course.
• You should go through the placement patterns of both the institutes for the last few years, including the packages and type of jobs offered. 
• The market credibility is also an important aspect to be assured of, which decides whether the degree certificate is worthy or not.

Considering the above factors, Symbiosis seems to be a safer option, being an institute with an established market value.