All three colleges are good engineering colleges and each of them has their unique pros and cons. For instance,
In terms of placements and academics, the preference order would be
In terms of campus life, the preference order would be
As a whole, NITs are well known for their excellent placements, brand name, faculty, and elaborate alumni network whereas Tezpur University is known for its widespread beautiful campus, research culture, and extracurricular activities.
So, you can choose the college that meets your expectations of college life.