Definetly IIT Guwahati CSE If by placements you meant Top MNC Companies with Coding Profiles like Google, Facebook, Yahoo,Amazon and hot startups like Flipkart

Although for Amazon it doesn't matter as long as you are good enough in Algorithms

For sitting in Day 0 Campus placement in these top companies you need to be CSE Undergraduate.

On the top of that you will be Studying CSE which you will be working in later part of life if you aim to be in these companies .

This answer is solely based on the Placement requirement.. there are cases where you have better life by opting Masters/PhD in Electronics (BioElectronics etc).

I have know people more than a few friends who are working in IT Industry coming from IIT Guwahati CSE / Roorkee ECE, based on their work satisfaction and Curretn CTC I am advising you to opt IITG CSE over IIT Roorkee ECE/Guwahati ECE if your ultimate goal is to be placed well at the end of 4years and have good work satisfaction.

But it all depends on what interests it you

• If you look mathematics and statistics opt CSE ( in Feature you might be working on Machine Learning Algoritms)
• If you are interested in physics of everything and like to work on chip level system design opt ECE, you might struggle a lot to study and usually your B.Tech is not enough to work in the same field