Hello,

If you are having chances of getting your desired course in NIT, then go for it.  I hope that you are aware about the test that to be taken after the preparatory course, if you are confident that you can pass the test then you go for IIT, but incase if you don't qualify the test then you will be kicked out. Or  like if you are IIT aspirant and want IIT tag to you and also if you are confident that you will pass the exam then go for IIT. But my best advice is to choose NIT. However, it is your decision, final choice will be in your hands.