Firstly IIITs are newly established colleges and hence they are far behind from good NITs. I have a friend in NIT Silchar. I heard good things about the institute from him. 

Here are some of the things that make NIT Silchar a good choice.

• It is 9th on the list of top 10 NITs.
• It is the second most premium institute in the northeast after IIT Guwahati.
• Placements here are top class with great infrastructure and world-class faculty.
• NIT Silchar is known for its Digital Library which is the biggest, not only in India but in entire South Asia.

You should go for NITs and you won't regret it. Rest depends on your research and feasibility.