Sir give the preference order- iiit Gwalior cse ,nit Silchar cse,IIIT Lucknow cse (new),IIIT Lucknow it,IIIT Guwahati cse,nit Hamirpur cse,
A lot of students face this kind of dilemma during JOSAA counseling. Since it looks you are more inclined towards CSE and IT departments you should go for a college that has a better coding culture. Among these colleges IIIT Gwalior has the best coding culture.
You can also have a look at the NIRF Rankings and decide the college:
If that is the NIT Silchar will be your best option.
Hope this helps and All the Best.