The certain winner here would be GNLU.
More batches have passed out from GNLU than NMIMS. GNLU also has better and more experienced faculties. Apart from these, GNLU is a well-established brand in the law education circuit. The campus, infrastructure, library, student quality is better at GNLU. You will get a lot more exposure, facilities, and opportunities at GNLU than at NMIMS.
Currently, there is a lot of room for NMIMS to improve. The classrooms are newly built and only a few batches of students passed out from NMIMS. Even though the student body is apparently doing well, it is yet to be established properly. The number of winners in MUNs, debates, moots, etc., is definitely growing but it still has a lot of work and improvements to do to become considerable. NMIMS is growing but to be as reputed and renowned as GNLU, will still take a lot of time.