Between Midnapore and JNM Kalyani, it is better if you go for JNM. This is because Midnapore is much farther from the city. The weather here is also harsh, The hostel and mess facilities are poor and not properly maintained. The Infrastructure is also average when compared to JNM. In the monsoons due to flooding, communications are lost. 

In JNM both the faculty and infrastructure are better and well equipped as compared to Midnapore. All the necessary facilities are provided for the students. Also, Kalyani is directly under the WBUHS hostel. Kalyani as a city is welcoming and easy to adjust to. It is also closer to Kolkata. Communications and transportation here are better. 

Therefore you can see the benefits of studying in Kalyani will be better than in Midnapore, hence it is suggested you opt for JNM Kalyani.