Rather than telling you what to choose, I will list down the pros and cons of both the B Schools and leave it to you to make the final decision.

Mannheim Business School, Germany

Pros 

• Being one of the most reputed B Schools in Germany, you will get a high-paying job right after completing your course.
• Mannheim itself is an experience as people from all over the world come here and you get to attend some amazing events too.

Cons

• This B School charges a whopping fee of around 32000-35000 euros. And the fees do not include living expenses (9000 euros)
• You will have to learn German especially if you want to get into product management to deal with clients. That is an additional expense.

IIM Bangalore 

Pros

• Fees are comparatively less than that of Mannheim Business School.
• Faculty is supportive and extremely experienced.
• Living expenses are included in the fees themselves.
• The placements are top notch and with an above-average grade, you can easily get placed at a reputed firm with a high package.

Cons

• Being located in the heart of the city the only disadvantage that IIM Bangalore students face is the heavy traffic.

Weighing both the pros and cons you can now make a decision easily. In my opinion, go for the German B School if you have plans for permanently settling abroad. But if you want to eventually stay in your home country then IIM Bangalore is the best option for you.