I’m a Chemical engineering undergrad from Pilani campus. Let me answer your question in parts.
Comparing Manufacturing, Civil and Chemical (Pilani campus):
It’s difficult picking the best of three. It’s better that I tell you alittle about all three and let you decide:
Manu has a lot of courses common with Mechanical, and a few extra ones of its own. This means that almost all the core companies that open for Mecahnical open for Manufacturing too. Take Manufacturing only if you are interested in how production machines are designed.
For Civil, there is a lot of field work. You are expected to do soil testing in the burning Pilani heat. But the branch as such is easy to score and better graded due to relative marking.
Chemical is where you will meet the ultra-ghots. The subject material is mostly theoretical, and often seems illogical. And as far as Pilani is concerned, this could well be the department with the most serious Profs. You might have a feeling sometimes that you are back to the school. Course is production of chemicals, fluid mechanics etc.