Hello !!!
You can see below the various jobs for both mechanical and  civil you can make up your mind by seeing this:
Mechanical

If you want a job in PSUs like NTPC, IOCL, SAIL, BHEL, GAIL ONGC etc. because vacancies in PSUs are very good in number

Vacancies are quite okay in ESE also
CIVIL

If you want a job in your state government like in state PWD, PHED, PRDD irrigation etc. In state public service exams vacancies for civil are more than for others.

In ESE vacancies for civil is also good comperatively.

In SSC also vacancies for civil is better than others.
Good luck!!