hello pydah, three of the courses are best u have choosen right option as all this are interlinked.according to me  If u have interest in measuring instruments which measures automated systems u can opt for inst enggbut  mechanical focus on design analysis and construction.. but there is more scope in mechanical area as there package is more for mechanical branch.

all the best

Actually all branches in engineering have equal importance.
What matters is that in which branch you have interest and you are comfortable.
E&TC and mechanical both are good branches.
You just have to think about your interest.
Hope this will help you.