greetings,

selection of the branch depends on your interest.

mechanical is to do with machines and electrical is to do with circuits.

if you want to prepare for upsc side by side, go for mechanical as it is comparitively easier.

you will be able to focus on upsc preparations also.

pls compare the syllabus of the two and then make a decision according to your comfort

http://dtu.ac.in/Web/Academics/syllabus/schemes/Electrical%20Engineering%20(EE)_06.03.18.pdf

hope this helps.

good luck

http://dtu.ac.in/Web/Academics/syllabus/schemes/Mechanical%20Engineering_Final.pdf