Alliance University used to be one of the best institutes for MBA in Bangalore. But, it has lost its credibility now. ISBR is also an average institute. However, ISBR is comparably better than Alliance University. 

I know a few students from both institutes. Based on their experience, placement record of the institutes, course fee structure, it can be said that ISBR is a better option. As compared to Alliance University, ISBR has better infrastructure, faculty, foreign exposure, and extra-curricular activities. 

Although apart from these two institutes, there are several other good options to pursue MBA in Bangalore. So, do your research and choose wisely.