Both IIT Kanpur and IISER provide excellent quality education but IISER has a slight advantage when it comes to the quality of research conducted.
IIT Kanpur
IISER
IISER provides an excellent environment for students who want to become future scientists and contribute to society. It will also open doors for Ph.D.
The 3 foundation Physics courses taught to all engineering students in the first year are Introduction to Mechanics, Introduction to Electrodynamics, and Physics Lab.
However, a BS in Physics is not a good choice if it's the placements you are after. It is a research-oriented program whereas IIT Kanpur provides an Engineering focused environment. So the best choice for a BS in Physics is IISER.
However, this is simply a popular trend, and you don't have to follow it. It is best to make a decision based on your individual preferences.
First you should make up your mind regarding the domain you want to continue with.
Here are some information to make your decision easier:-
This is slowly becoming one of the most coveted branches of IIT Kanpur. All the software companies that open job profiles for Mechanical and Chemical students also offer roles to students of BS in Physics. In fact, you will be surprised to know that many software companies opened profiles only for CSE, EE, Mathematics, and Physics, and not for mechanical, chemical, or civil. So we can conclude that BS in Physics is considered even better than Mechanical and Chemical to a certain degree.
IIT Kanpur is second only to IISc in terms of global recognition and foreign education opportunities. It gives a constant edge to IISc in the quality of its research work and the overall standard of the institute.
While many may not agree, in my opinion, IIT Kanpur is even better than IIT Delhi or Bombay.
On an ending note, I would like to comment that make sure you go through the coursework once because the program comprises in-depth Physics concepts that everyone cannot handle.
IIT Kanpur is a better choice if you want to opt for theoretical physics (especially quantum mechanics) than IISC Bangalore.