Which should I pursue between mechanical at UIET Chandigarh and metallurgical engineering at PEC Chandigarh?

Surely, Metallurgy at PEC over Mechanical in UIET. There are various important reasons behind this: Placements in PEC are better, companies like Google, Amazon, Microsoft, etc. visit campus for placements.

Though metallurgy has fewer placements than other branches in PEC, once you are in PEC and if you are focused enough, you can go for an upgrade after 1st semester on the basis of CGPA. To aim for it, keep the following things in mind -

• At most, only the top 10% of the class can be upgraded.
• The branch you want to be upgraded to will only be available if it has vacant seats.

PEC is far superior to UIET in terms of cultural and other extracurricular activities. If you don't have any branch priorities, I'd recommend metallurgy in PEC.