Should I go for MBA from NMIMS Mumbai or take a job and try again next year?

 If you are certain that you will be accepted into IIM A, B, or C, or FMS, then the only time I would suggest dropping NMIMS is for that purpose. It is not a good idea to skip over the top 15 in favor of the top 10 unless your goal is to be at the very top. 

There are no other IIMs, and there are no other private colleges. I am not claiming that NMIMS is the next best thing after A, B, C, and FMS, but the gap between NMIMS and the rest of them is not significant enough to warrant skipping a year. They all offer learning and placement opportunities that are comparable, and once you've moved on from your first job, the value of the brand will no longer be relevant.