I will be shortly completing my B.Tech from NIT Calicut. I have a CGPA of 9. Is it better for me to join for M.Tech at IIT or MS from a foreign university?

It depends on your interests and your financial background. There are many reputed institutes in India where you can do your post-graduation. However, some institutes in the USA and Germany have an international reputation because of their technology and facilities. That is the reason why many graduates choose to do their MS from abroad. The availability of great placement opportunities is another reason. However, before deciding on anything, research the market trends in India as well as abroad to get an idea of the placement opportunities available.