Hey Parthiv,

CSE or Mech. Its basically core branches and non core branches. 

So currently in engineering trend is towards non core branches as mostly due to tons or start ups jobs placements are more. But I'll never recommend you unless you are interested In Computer as the status of placements are of current and You will pass out after 4 years an the things are gonna surely change. So better don't go behind the crowd and placements choose what's best for you.

About mechanical it's an evergreen branches but less placements is the problem. As the number of students in past was high same as it is in CSE today. 

So choose with care.

Best Of Luck