Between IIIT Bangalore, MNNIT Allahabad, IIIT Allahabad, and VNIT Nagpur, which college should I choose for CS/IT engineering?

Your preference order should be IIIT A > IIIT B > MNNIT > VNIT.

• IIIT A: IIIT A is one of the best in the country for IT courses. The campus and facilities are amazing. The culture of coding is great there. It is one of the top competitive coding locations online. 
• IIIT B: IIIT B is also a decent option, however, it ranks a little lower due to its small campus and college life. Also, the course is a dual degree program and quite new, for this reason, most people don’t opt for it. But it is a pretty good option if you are passionate about CS and want to do MTech in the future. The faculties are great. The course curriculum is updated with many elective options. 

Both these two institutes teach core CS/IT subjects from the first year itself. If you are genuinely interested in CS/IT you can choose either of these two institutes.