Which stream should I opt for in M.Tech to get a good job in the teaching field, thermal, design, industrial or automobile engineering?

If we go through the current trend, you can have better prospectus in the field of product designing and industrial and automobile engineering.

Hello Mayank, It's great to see someone to be interested in M.Tech to get into teaching field. You should choose as per your interest, skills and capabilities. Also, you should as per where are you willing to work, in India or abroad? In India as per the preferences most common and popular courses

As per me, you should opt for product designing course. It has a good scope.