IIIT Allahabad is the best option among these for IT. It offers better academics, research opportunities, and placements. 120+ recruiting companies visit IIIT Allahabad placements each year. The average CTC for the branch is around INR 21 LPA. Every year more than 90% of students get recruited from the IT branch.
All three institutions provide top IT courses. Let us compare the institutions based on the following factors.
Placement: (Winning Institution - NIT Surathkal)
You can check the official websites of the respective institutions for further details.
Infrastructure: (Winning Institution - NIT Surathkal)
Faculty: (Winning Institution - MNNIT)
MNNIT bags first position in this case, NIT Surathkal stands on the second position considering it has a lesser number of IT faculty.
Curriculum:(Winning Institution - NIT Surathkal)
It is not apt to call one institute the best among the given three. It is all about choices. You can go to NIT Surathkal if you are a smart and ambitious person. But, if research interests you, IIIT Allahabad and MNNIT are better options.