Both are not a good option.
M tech is good only if done from IIT or NIT.
M tech from private college will not help you.
I did an M tech from RVCE.
Many of my classmates and me didnt get placed.
As a matter of fact we all wasted 2 years and 2 lakhs.
Its better to get a job after B tech and gain experience and invest in skills
Additional degree never helps much unless you have plans to get into teaching.