I know that there are university rankings and department rankings, but I’ve heard a lot of people say xyz university is better for Networking or abc is better for VLSI. What are these people basing it on? Research going on at these universities or job opportunities or courses offered? How many attention should one pay to these things if it’s at some place like Cornell or Northwestern or UCLA?
Not much!
Those comments will be based on the faculty and expertise in the discipline at the school. Look through the faculty lists, and even at the biggest schools, some disciplines are very poorly represented. Generally, each department will have its strengths and weaknesses. USNews somewhat ranks specialties (in a general way) for their grad school rankings, and in my field (chemistry) they are acceptably accurate/maps onto my personal impressions.
If you’re going for a PhD and you know there’s a particular discipline you want to specialize in, then the differences matter. Sometimes a lot. For example, in my field, if I wanted to work on molecular machines, I given the schools you’ve listed, I would go to Northwestern or UCLA because there are multiple very prominent researchers working on that at each of those schools. If I wanted to study polymer synthesis, I would probably go with Cornell followed by Northwestern. At the PhD level, you should seriously consider the advisors available to you at each school - what stage of their career are they in, what specifically are they working on, would you learn what you want to learn in their lab, etc.
Usually these rankings are a poll of faculty from other universities. This is not necessarily very scientific and usually depends mostly on research expertise. If you are in a coursework only degree, it is more important to look at the courses you are expected to take and at the internship and placement possibilities.
And the placement and internship possibility would be affected by how close the university is to a city? (Given my field is Electrical and Computer engineering)
Depends on the program. For top-tier programs, it matters less where the program is located - they have structures in place to get their students into the best internships and job placements. For mid-tier programs, the location may have a much stronger effect since many companies do fill part-time positions and internships sometimes by pure availability and proximity.
However, location does always provide an advantage for networking (that’s just way easier if you are right there) and for internships and part-time positions during the academic year (as opposed to the summer).