NIT Surathkal is ranked 13 in India for BTech by NIRF 2020. Whereas, NIT Nagpur is ranked 27 for the same by NIRF 2020. NIT Nagpur also ranks 3rd in Maharashtra by NIRF 2020 and has collaborated with many industries and R&D organizations.

As the courses in the question are not the same it is tough to evaluate which institute will be better. Here is some of the important information about the two courses which may help you in making the decision. 

Admission:

NIT Surathkal:

The mechanical department at NIT Surathkal has produced over 4500 mechanical engineers graduates across the nation. It offers a BTech program for Mechanical.

• The essential eligibility criteria for admission is 10+2 in the science stream, with a minimum of 75% aggregate. 
• The candidates’ selection is based on the JEE Main score, and the seats are allocated through JoSAA counseling.

NIT Nagpur:

CS department at NIT Nagpur has well-qualified, motivated support staff and faculty members.

• Admission to the BTech CS program at the institute is based on the marks obtained in JEE Main. 
• The final selection is based on the JoSAA counseling round. 

Placements:

• The placement average for NIT Surathkal is 100%, whereas at NIT Nagpur the placement rate is 85%.
• The highest CTC received by the students of NIT Surathkal is INR 39 LPA. The highest CTC offered at NIT Nagpur was 52 LPA.
• The top recruiters for mechanical at NIT Surathkal are Tata Group, Godrej, L&T, Thermax, Google, Microsoft, Apple, Ashok Leyland, General Motors, etc.
• The top recruiters for CS at NIT Nagpur are Goldman Sachs, JP Morgan, Infosys, Dell, Deloitte, Capgemini, Thermax, ZS Associates, etc.

In terms of industry trends, CSE is in more demand than Mechanical engineering. Both the NITs are reputed and offer decent academics along with good placement opportunities. However, you should choose the stream in which you are more interested.