Both the institutes mentioned by you are equally good and thus it will be very difficult to tell which one will be the best option. However, we can help you with the parameters that you can keep in mind while choosing an institute among them. You can consider the below parameters :
1) Faculty,
2) Affiliation / Recognition
3) Course Material,
4) Quality Education,
5) Fees
6) Infrastructure
7) Success Rate.
8) Placement
9) Top recruiting companies.
Also, if possible go through the alumni speak section to get an idea what the alumni thinks about the institute.

Considering all this, one can safely assume IHM Bangalore is better.