For obvious reasons, IIT Bombay is a better choice than NIT Silchar.

• Bombay has much more locational advantage than NIT Silchar
• The teachers are experienced unlike in NIT Silchar wherein the teachers are still completing their PhDs from MIT, CalTech & Stanford.
• IIT Bombay has higher JEE rankers even higher than NIT Silchar
• IIT Bombay has much better companies that visit the campus for placements like Google, Microsoft, Credit Suisse, Intel, etc.
• IIT Bombay has better infrastructure and amenities than NIT Silchar such as swimming pool and multiplexes.
• IIT Bombay has better foreign exchange programs than NIT Silchar
• IIT Bombay has richer research culture than NIT Silchar
• The Mood Indigo fest is more vibrant and famous than the Incandescence fest of NIT Silchar

I would suggest you go for IIT Bombay over NIT Silchar any day.