My son is ranked 17401 JeeM 2019,he is interested CSE.which one is better NIT agartala or IIIT Gwalior, IIIT Kanchee, IIIT Kottayam
Congratulations on your rank!
Since you have not mentioned your category here, the query would be answered by considering the student as a general category student.
Here, you have asked for comparison between NIT Agartala, IIIT Gwalior, IIIT Knacheepuram and IIIT Kottayam so let us begin with NIRF ranking first.
NIT Agartala has been ranked 70 by NIRF. With a rank of 17401, the student has high chances of getting CSE seat at NIT Agartala. NIT Agartala is old and well established. It is good for CSE. With placement points of view, it is also very good as companies like Oracle, Capgemini visit the campus and recruit students.
IIIT Gwalior is new and very good for CSE. It has been ranked 81 by NIRF, but according to 2018 cutoffs, the student may not get CSE there as the closing rank for CSE was 12292, but you can get integrated 5-year program of B.Tech+M.tech in I.T. at this rank at IIIT Gwalior.
At IIIT Kancheepuram, you can get CSE according to 2018 cutoffs as the closing rank was 18297 for CSE. IIIT Kancheepuram has been ranked 197 by NIRF. It is also good for CSE.
IIIT Kottayam is new and yet has not been ranked but it is growing rapidly with good faculties and other facilities. It can also be considered good for CSE.
This was a glimpse of comparison between all the given colleges. Choosing one is your choice.
I wish you all the best and for any further queries, ask me in the comments.

Eagerly waiting for your reply