dear student,

in terms of placement I think the top NITs are just as good or even better than engineering colleges bar maybe some IITs. This is because they have developed a brand image over the years in the corporate world due to their illustrious alumni. However, an IIT (old or new) comes with much higher funding, and will in the long run have better facilities than the NITs. NITs have been envisioned to provide quality B.Tech education to the students and they do just that. They offer very little in terms of Research or Industry Collaborations. By virtue of existing for over 50 years, they have developed campuses but also problems of their own. 

hope this helps!!