I will always suggest you give preference to the branch over the college. NIT Jalandhar and NIT Raipur are better colleges for CSE than NIT Patna and NIT Silchar. Another good option is ECE at NIT Allahabad or NIT Calicut as most of the companies let ECE students sit for software engineering roles during placements.

I am strongly against you joining mechanical engineering if you are already getting CSE/IT/ECE at NITs. Ultimately, it’s your preferences that will help choose the best college!