compare Electronics ( ECE) and Mech or civil, Instrumentation options are limited. but same time it is most important requirement for the process industry. you will have option to join C&I manufacturers like ABB, Siemens, Emerson, YBL, etc. all are giants in the market. All process industries and Power plants will have C&I departments and recruits, prefers C&I engineers. some people prefer Electrical and C&I common experts. Govt side chances are less in this field. Only NTPC, BHEL recruits people from C&I branch, however you will have option of private sector where lot of MNCs are present as described above.
I am an instrumentation engineer worked in ABB for 20 years now working in a MNC.