Both Jadavpur University and ISM Dhanbad are reputed institutes. ISM was already quite reputed across India and after getting the IIT tag, the institute has improved quite significantly. 

• If you are getting branches like CSE/ECE at JU and offbeat branches at IIT ISM, then you should definitely choose JU. 
• Another advantage of choosing JU is the negligible fee. For a 4 year long B.Tech you will need to pay only around 10,000. 

So, take these factors into consideration, and choose according to your convenience.