Which is best, CSE/ECE at JMI Delhi or IET Lucknow?

I would suggest you to go for JMI Delhi. The reason for this is that JMI is very similar to the NITs. The environment and crowd are top-notch. Seniors at Jamia are also very helpful and cooperative. 

The professors and other members of the faculty are well-experienced. They even help you plan your career after college. JMI alumni help you out in getting jobs and a decent salary amount.

The table below depicts the placement scenario of JMI and IET:

Though it is your decision to make, I still would prefer the fact that you choose JMI Delhi over IET Lucknow, for CSE or ECE. Studying in a well-reputed institution with years of educational experience is much better. This will help in networking as well.