I feel you are torn between the IIT and NIT tags here. In that case, new IITs are a better option unless you are considering top NITs like Warangal, Surathkal, or Calicut.
But it seems you have 2 generation NITs in your list only. In that case, IIT Mandi is a preferable choice.
Either program will offer a plethora of opportunities, and choosing one over the other will be merely because of personal preferences.
If you are confused between IIT Mandi or NIT Bhopal, choose IIT as the primary option.
Being an IITian has its own advantages. You will receive more reward and respect from society. One of my relatives from Biotech is pursuing his Ph.D. from Heidelberg Germany Berlin at the age of just 26. He visited almost 21 countries already for academic purposes. He also attended many Ivy league colleges like MIT, Harvard, Princeton, Stanford for conferences.
IIT Mandi is very good at academics. The faculty here are very experienced and friendly in nature. They teach the concepts in a very easy and simple manner.
Also, if you want to pursue higher studies, then choosing IIT will be better.