Mostly,people think IITs are the best institutes in India. The main reason behind this is:Coaching centers. They've marketed a lot about IITs. While IITs are very good institutes, at the same time people should know about other institutes like:ICTS,TIFR,HRI,IUCAA,IMSc,RRI,ISI etc

IITs are good for engineering, and they've even contributed a lot to pure sciences. But above mentioned institutes are underrated due to less marketing which have contributed to pure sciences more than IITs. In addition to above, IISc and IISER are also world class institutes.

This should also be known to common people. For some reasons, some people think only IITs are everything. But at the end of the day your performance & project guide matters not the name of any institute.

Homi Bhabha National Institute(HBNI) includes these prestigious institutes:SINP,IPR,HRI,IMSc,NISER etc. These along with ICTS,TIFR&IISc produce high quality research in Physics than IITs.

According to nature index: IITs are very below in the rank-list compared to these institutes, at least for physics. As you can see, some state universities & newer IITs produce better output than IITs !!
https://www.natureindex.com/institution-outputs/generate/Physical%20Sciences/countries-India/All/n_article

ICTS, Banglore(best for theoretical sciences on any given day). TIFR Mumbai - well known research institute for theoretical physics,biology,mathematics & computer science.HRI(best for mathematical physics,string theory/Quantum Information)

IMSc is very good for mathematics and theoretical computer Science and other mathematics relate fields. RRI - For condensed matter physics. ISI - best for data science,Machine Learning/AI, Statistics & Cryptography.

These are better institutes than IITs in their respective fields. IISc is very good also, in physics - it is good for condensed matter physics only ,other physics branches are not very good there on average..

IUCAA is internationally renowned and best institute for astrophysics in India. India don't have any science reporting media yet and lacks reputed scientific journals which gives very false impression to people that not much scientific excellence produced by Indian Scientists.

If someone wants a good job in industry, however, http://B.Tech . from IIT will help more. But if you can't get IITs, in the long run - it doesn't matter. And to get into research&academia, IIT tag never matters.

Geting into IITs is like getting into U19 team. If one performs well in domestic tournaments/Ranji he might be selected for Indian team. So beware of this propaganda run by coaching centers and make your own path.