Hello Murali,

From what I have gathered during my interactions with fellow undergrads at IIT BHU and IIT Roorkee, it can be safely stipulated that the 3 institutes are almost comparable in all aspects.

The placements in CSE are equally good at all these institutes, and the research is equally poor, though it has been improving over the last couple years. It may be argued that IITR has a slightly better competitive coding scene, but with an increasingly active Coding Club/ CSEA at IITG, that is probably set to change in the coming years.
Good Luck!