Which college is preferred in case of B.Tech.

Topmost colleges in India for B.Tech are the IITs, followed by NIT, IIIT and GFTI.

IIT's are the first choices, then comes the NIT's, also there are some private colleges like VIT, BITS, that are preferred for B.Tech, then state government engineering colleges.

You would have to be more specific. But, generally, IITs come first and then there are the NITs aswell.