Which is a more rewarding city to visit kolkata or Mumbai?

It all depends on what person you are. I have been to both, and although they are very different, you need to weigh up your options. I see that if you were to go to one, do your research and make sure the country you are going to is the right choice. I personally enjoyed Mumbai the most, however you can always go to the next country next time :) Hope this helped a little..