It all depends on the definition of best.best, in terms of placement ——-IIT Bombay
best in terms of research————IIT Kanpur
Best in terms of Infra is faculty IIt Mdras (also best if you’re planning to do a phd).
You are an undergrad student, and once you visit any of the iits, you will see that there is no best or worse. It is entirely up to you to decide what you want from it.