What is the best university for post graduation

What is the course of study?

That depends on many factors. What degree do you have? What are your interests? What area do you want to go to? Price and Reputation are also things to consider. What kind of environment do you want? Are there other people similar to yourself there?

Anything such as the above that is important to you, will help make that decision. You also have to decide if you can get accepted for your course of studies.