As far as the college rankings are concerned, most of the IITs perform better than NIT. IIT itself has a brand value associated with it.Being a IITian myself, I would suggest of getting into IIT but only when you are getting the branch which you are interested in. However, various clubs and groups are also present which help in overall development in each aspect be it academics, sports and extracurricular activities.

Now a days, BTech is preferred by those who see their future in corporate sector. After BTech one can go for MBA or directly get placed and earn. While those who are more interested in research and experiments, then I will suggest them for BTech + MTech and then they can go abroad for further research or PhD.