Is Sastra University better than NIT’s?

Based on various parameters like salary packages, peer group, etc. NITs are definitely better than SASTRA. 

However, SASTRA is also a reputed university, especially if we talk about research facilities. It has a great research infrastructure. The faculties are also good. Many of them are IIT or NIT alumni. The faculty research outcome of SATRA is similar to that of NIT Trichy, in terms of citation. 

Alumni of SASTRA are pursuing their studies in reputed universities around the world like MIT, Caltech, Harvard, etc.