Which college should I choose: Jadavpur University CSE or NIT Trichy CSE in terms of placements?

Both institutions offer great research and placement opportunities in the CSE branch. NIT Trichy gets you an INI Tag and the hostel-life over there is great. On the other hand, the fees at Jadavpur University are incredibly low. Also, Jadavpur University allows you to experience University culture. 

I personally know alumni from JU and NIT Trichy CSE and all of them are doing well in their careers. I would suggest you talk to the recently graduated alumni from both institutions to get a closer look at the present-day ground reality.

According to me, whether you choose CSE at NIT Trichy or Jadavpur University, you will not regret your choice. Also, consider other grounds like location before arriving at the final decision.