NMIMS bangalore is an old institute compare to NMIMS bangalore. so the placement cell is more established and it is thus well connected with industries. Comparison on the basis of placements is as follows  -

1. NMIMS Banglore - students received an average salary of INR 11.80 LPA which is 9.8% higher as compared to last year. The highest & median salary increased by 22.4% & 12.1% respectively. The highest salary offered was INR 19.58 LPA & the median salary stood at INR 10.65 LPA.
2. NMIMS Mumbai - As the University claims ,the highest salary package offered was 16 lacs per annum and the lowest salary package offered was 6 lacs per Annum.The average being roughly 11 lakhs here as well .

As we can conclude from the above statements , both of them are equally good in their packages and placements , despite of that fact according to me you should always focus on the main branch i.e Navi Mumbai , as it was established first and we cannot ignore the fact that main campuses are always given a reputation advantage over other branches of the same institute .