Hey

If you are getting decent NIT with your desired branch then you can go for NIT , else if you wanna drop an year for IIT then you can do that as well.
To check which NIT you are eligible for,  you can check through previous year cutoffs on the following link
https://www.google.com/amp/s/engineering.careers360.com/articles/nits-cutoff-for-top-btech-branches/amp

Hope this solves your query.
Good Luck!!