Hi Shweta

As you have qualified JEE advanced and you want to go for CS branch, I would suggest take the jammu IIT college with your preferred branch because dropping that only because it is not top of IIT would be not appropriate.

As if you have passion in particular field then whichever college you get is not much imp, you'll do great in any of it. And I believe branch over college. Although its upto you whether you are happy at particular place. Also Jammu IIT is also good in terms of academics also so you should go for it.

Hope this information helps!