Which is better - doing M.Tech from IITs or going for NITIE Mumbai?

Having to know some people studying in both these colleges, I can say that they are equally good. You can opt for any one of them, their respective programs are also good. They are recognized as Centres of Excellence by MHRD, Govt of India.

The choice mainly depends on the individual and their preferences. You should go for the one you are enthusiastic about.

• NITIE offers 3 courses, where the selection is through GATE scores.
• These include Post Graduate Diploma in Industrial Engineering, Project Management, and Manufacturing Management.
• These courses are a mixture of technical and business management.
• IITs offer M.Tech through GATE exam scores. 
• It involves core specialization and nothing about industrial management.

So, the selection of the college and the course entirely depends on you. Go through them and then decide which will be a better option for your career.