ISI is an Institution that is controlled by a single governing body but has different centers, unlike IITs which are governed by independent bodies. 

This means, no matter if you study from any branch of ISI like Bangalore, Delhi, or Chennai, you will be awarded a degree from ISI Kolkata only because that’s the headquarters.

Therefore it makes no difference between the curriculum and value of both ISI Kolkata and Bangalore. The only difference between the institutes lies in the course that they offer. ISI Bangalore offers Bachelor’s course in Mathematics whereas, ISI Kolkata offers Bachelor's course in Statistics.

So, the choice of institute totally depends on whether you are interested in statistics or mathematics.

One of my cousins is a recent alumnus of ISI Kolkata and mentions that there have never been any complaints regarding ragging. 

Most essentially, there is a legitimate reason behind these institutions being different from many others. That being said, ISI, CMI, IISC, IMSC, TIFR, and HRI are mostly different from every institute because they are primarily research-oriented. The list also incorporates IIT, NIT, BITS, IISER, NISER. These institutions are completely free of the Students Unions Ragging, students clubs, and more. 

Having to know some people studying at both Simsree and KJ Somaiya and here are some things that you should know. They both are equally good.

• Both the institutes, for their MMS course, teach the same syllabus specified by the University of Mumbai. So, according to the content, there is no difference.
• This is generally a good thing that you are specializing in something that roughly 4 to 5% of the batch will specialize in. 
• It is not as difficult for the placement committee to get companies with specific profiles.
• The institutes have been there for a fairly long time and both have a steady pool of recruiters. Therefore, placements are not very problematic. 
• Having said that, placements depend on multiple factors, and nothing can be guaranteed.
• K J Somaiya has more full-time faculty members whereas SIMSREE has more visiting faculty members. But cannot say the same about the operations specialization.

Irrespective of where you go, your responsibility is to get better, participate in competitions, do certifications, and improve yourself holistically. The institute cannot impose anything if you have no intention of doing it.