Hi

I would suggest u fr IIIT Allahabad,as it is one of the best institutes fr IT & CS studies. It has gt excellent record and placemment scene, so going fr it, compared to lower NITs is good. If u get a good branch in NITs lyk Trichi , Warangal or surat, then do prefer NIts over IIIT A.  Please read the foll article as displayed on IIIT A site:

IIIT ALLAHABAD RANKED 8TH BY INDIA TODAY 
India Today, India's leading magazine has ranked IIIT Allahabad among the Top 10 Engineering Institutes of India.

It has been ranked 8th after the seven IIT's. The most important fact to be considered is that IIIT-A is the youngest institute to be included in India Today's top 10 ranking. It was established just 8 years ago in 1999.

Last year also IIIT Allahabad was ranked 11th by Nasscom-Dataquest ranking and was ranked 4th by the same in Placements. It is a matter of fact that IIIT-A has one of the best placements in India as many of the leading companies of the world visit the campus for placements.

IIIT-A students have made their mark in every field related to Computer Science and Information Technology.
It has produced one of the best programmers from India with one of the IIIT-A teams representing India in the World Finals of the 30th ACM International Collegiate Programming Contest.

Even this year there are a number of achievements to be counted latest being a IIIT-A team winning third prize at Microsoft Imagine Cup Software Design Contest.