Hello aspirant!!!  Well it is a matter of personal preference. If you are really bend on do cse then you should choose IIT Bhilai. On the other hand if you wish to study in a better college then IIT Bombay would be the right choice. Remember that you can change your branch if you perform well in college so I think that IIT Bombay has slightly better edge here. Although the choice is obviously up to you. Hope this helps.