Hello Mann!

It highly depends upon your interest. I am giving an Idea of each branch which may help you in deciding that what branch is better for you-

B.tech Electronics

Electronics branch deals with the study of Electronic circuits, VLSI design, etc.

You would be having great chance in Cellphone industries and PSUs such as ISRO, DRDO, etc.

B.tech Mechanical

In Mechanical you will study Machine designing, Robotics, etc

You would be having good chance in PSUs as Mechanical students have lots of opportunities there.

B.tech Mechatronics

Mechatronics is a field which is originated from the combining of Mechanical and Electronics branch.

Here mostly Robotics is taught. You will learn to manage or create Machines via Electronics knowledge. 

Just think about the field which interests you. That will be the best field.

Hope that helps!