Hello, 

As you have mentioned that your jee main AIR rank is 12258.At this rank you can get admission into any one of the prestigious nits but not get every branch.Home state and other state quota always matters for taking admission.

If you want to give preference of college over branch then some top nits like nit trichy,nit Warangal,nit surathkal,nit rourkela etc are better.here you can get some branches like Metallurgy, BioTechnology, production, textile etc

In these colleges you can also get civil and chemical if you want and wait for 7th round.

If you want to give preference of branch over college.For branches like mechanical, electronic and communication, electrical,etc some colleges like mnit Jaipur,Manit Bhopal,nit kurushetra,Vnit Nagpur,mnnit Allahabad are better.

For computer science some nits are nit Jalandhar,nit Jamshedpur,nit hamirpur,nit silchar etc are better.

To know about NIT Agartala, you may visit the link given below :

https://engineering.careers360.com/articles/jee-main-cutoff-for-nit-agartala

I hope this would help you. For further queries please feel free to write me down in the comment box.