I would recommend ECE at IIT G if CSE is not your top priority instead of CSE at IIT BBS because IIT G being older has a very large alumni base plus more recognition among companies than IIT BBS. But if you take CSE at IITBBS you will not regret as placements are very good with high package . Since IIT BHUBANESWAR was started in 2008 you will get a permanent campus and almost all facilities of IIT G. Choose according to branch preference as both college are good and you won't regret your decision taking any of these.

( IIT Bhubaneswar was damaged in cyclone Fani I hope they finished reconstruction of damaged structures )