In the year 2020, the ranking of IIST was #33 by NIRF for B.Tech courses. On the other hand, MNNIT Allahabad was ranked #48th by NIRF for B.Tech courses. With excellent teaching staff, IIST is the 1st space institute in Asia to offer programs in space science and technology.
Admission:
IIST:
MNNIT Allahabad:
Placements
Choosing the subject depends on the individual itself. IISR will be really good if the candidate is very much interested in space and technology, as the institute primarily focuses only on space studies. Being a part of the 1st institute in the world to offer complete range of programs in space and technology will be plus point. Late Dr. A. P. J. Abdul Kalam was the former Chancellor of the University. The city life of Kerala is much better than Allahabad. Now, based on all the data and their interest the candidate can choose the subject and institute accordingly.
M.Tech from IIT Bhubaneswar makes sense only if you are willing to study more on research-based topics of the subject. It is best if one is looking for a career in Teaching, Researching, etc. to further gain knowledge about the subject and not work in MNCs.
IIT Hyderabad ranks 8th in the Engineering category by NIRF 2020. The number of students who got placed from the Chemical Engineering department in the 2019 placements was 26. The average salary package offered to students with Chemical Engineering is 15 lakhs per annum.
IIST is a space institute under the Department of Space. The students from IIST are recruited as scientists and engineers in the Department of Space facilities and Indian Space Research Organization centers all over India. They receive a starting salary of 10 lakhs per annum. Facilities like Infrastructure, Library, sports facilities, Computer labs, clinics, Data centers in IIST are much better and well equipped than the IITs.
Thus it is your choice to opt for what course you are interested in.