Which is a better option: aerospace engineering in IIT Kanpur or production and industrial engineering in IIT Delhi?

IIT Kanpur has several advantages over IIT Delhi. A few are mentioned below:

• Unlike IIT Delhi, branch change facility is not restricted to the first year only and one can change branches even after the 2nd year 
•  IIT Kanpur offers an enriched campus life with great relations between students as well as students and faculty. 
• There are no LAN restrictions at IIT Kanpur whereas, IIT Delhi restricts usage of LAN from 1 a.m. to 6 a.m. 

Lastly, once you enter IIT, your branch rarely matters. Your placements solely depend on your CG, your skills, and the efforts you invested throughout. So, go for a branch that matches your area of interest and you are good to go.