My younger sister has enrolled in the CSE program at NIT and it has excellent facilities for the program. The brand name of NIT and IIT is still more popular for some of the engineering aspirants because they lack awareness. Even my sister thought so before admissions, but NIT ranks #16 on the NIRF Engineering scale, IIIT A ranks #103, and IITs are usually in the top 5 in the same. 

Furthermore, your decision may change based on the following-

• The location of IIIT Allahabad is a factor contributing to its low popularity. It is located in a small village area called Jhalwa. There are no recreational facilities around and the only eating outlets are MacDonald's and Dominoes, which harm in the long run.
• The placement statistics of IIIT A show that it has a good 96% placement rate, but not many top companies come to visit because of the location. Networking is not an issue, but an institute in a developed area would have easy accessibility, lectures by renowned faculty, spots of refreshment; which are not present here.
• The hostels are not very good and those who reside in them, face difficulties related to social outings.
• Another fact of importance is that this institute has only two departments: Information Technology and Electronics and Communication.

You can see below, the comparatives of the institutes:

As you may see, IIIT A and NITs have excellent placement rates. The faculty will be more brilliant at IITs but students are dissatisfied even there. So you can see for yourself according to location, placement scenario, and brand name if that matters.

Well that is neither difficult nor simple. It actually primarily depends on how many students are opting for IT in IIIT Allahabad. It is almost impossible to guess what the cut-offs are going to be. Although there is a tough competition among students who wish to go for IT from ECE and you will have to clear that successfully.

How many students in your year are wishing to transfer from IT to EC will also matter in this aspect. Hence, rather than planning and thinking about what the cut off will be, the only thing that you should be doing is working very hard to score the best CGPA in your batch because only that is in your hands. Scoring CGPA above 9 makes it very easy for you to transfer from ECE to IT in IIIT Allahabad.

Obviously you should have all the basic knowledge and understanding such as C, C++, Java etc. before you think of switching your branch.

If you had specified the parameters on which you are judging the institute, it would have been easier to answer the question. In terms of quality of education, the two IIITs are better than the three NITs. 

Given below is a brief comparison of the institutes based on various parameters. You can make your decision based on that. 

Faculty:(IIIT Delhi > Top NITs ~ IIIT Allahabad)

IIIT Delhi has the best faculty. Even top NITs don’t come close to IIIT Delhi in terms of faculty. 

Campus Life: (Top 3 NITs > IIIT Allahabad > IIIT Delhi)

The top 3 NITs offer better campus life. As compared to NITs the workload of IIIT Delhi is too much. IIIT Delhi also does not have as many clubs and societies as top NITs. NIT campuses are also bigger in comparison. 

Hostels: (Winning Institute - IIIT Delhi)

• IIIT Delhi has better hostel facilities as compared to any other Govt. college or even some IITs for that matter. In summer you will get air conditioning and a heater in winter at IIIT Delhi. There are also sports facilities like Foosball and Swimming Pool, etc. 
• Other facilities available at IIIT Delhi are quite similar to that of NITs and IIIT Allahabad.

Placements: (IIIT Delhi ~ Top NITs ~ IIIT Allahabad)

In terms of placements, IIIT Delhi matches the placement statistics of top NITs. A student of IIIT Delhi has recently secured a placement package of 1.45 Crore. The average package of the institute mentioned in the question is around 15-17 lakhs (for CSE). 

Location: (IIIT Delhi > Top 3 NITs ~ IIIT Allahabad)

• IIIT Delhi enjoys the benefit of being situated in the capital. The city life, start-up culture, and many internship opportunities are some of the perks of attending IIIT Delhi. 
• Whereas, the top 3 NITs are situated in small cities. IIIT Allahabad is also located in Prayagraj, which does not offer a good city life or enough exposure. 

But whether you will like the campus or not depends on your background. If you are from South India, life in Delhi or Prayagraj may not be that appealing and vice versa. 

Reputation & Alumni Base: (Top 3 NITs > IIIT Delhi > IIIT Allahabad) 

• The top NITs have more recognition among the recruiting companies due to their legacy. IIIT Delhi is a fairly new establishment in comparison. Even though it is growing at a rapid pace, it is still up to the standard of the top NITs. 
• The alumni base of the top 3 NITs is also better due to the same reason. 

If you are genuinely interested in coding, you should choose IIIT Delhi or IIIT Allahabad. Otherwise don’t go for IIITs.

Dr. Rahul Kala- assistant professor at the Department of Artificial Intelligence and Robotics is one of the faculty members at IIIT Allahabad. He indeed is one of the finest of all. Here are something you should know about him -

• Dr. Kala completed his 5-year integrated B.Tech (IT) and M.Tech (IT) program from IIIT Gwalior. 
• Dr. Kala also has a Ph.D. in Cybernetics which is from the School of Systems Engineering, University of Reading, UK. 
• Pattern Recognition and Classification, Intelligent Vehicles and Intelligent Transportation System, Robotic Motion Planning were areas he had done extensive research in. 
• There are a good number of books and research papers written by him. 

Naturewise, Dr. Kala is one fine person who is so very humble and simple in his ways. Unless he doesn't have any lectures or meetings to attend, Dr. Kala arrives at his office around 9:00-9:30 AM and departs right at 9:00 PM in the night. 

He can be described as someone who is-

• Down-to-earth 
• Known for his candor amongst both his students and colleagues
• Extremely passionate about what he does. He learns at once and makes decisions accordingly
• Would always be seen either going through certain research papers, AI Books, Thesis, etc., and scribbling some technical formulae on the whiteboard in his office which no student would be able to decipher and wonder why even did they opt for Robotics in the first place. 
• Even if you decide to barge into his office unannounced, he would never mind that and would be ready to help you with your thesis or coding.
• Even if it is a teacher or even a student, he would always be a great mentor to them 
• You'd always find Dr. Kala wearing a smile and would never find him cranky. He is someone who would also lighten the mood of the class by cracking a joke 

To capsule everything about Dr. Kala, the point that I've tried to make is that you'll receive the best guidance and learning from him. His company is always appreciated. Whether it is anyone from their labs or lecture rooms- they'd always praise having Dr. Kala around.