Hello!

The best IITs for pursuing Mtech computer science are as follows:

• IIT Bombay: it's the best of all. The academics and research are great in all the IITs, there's no doubt about it. But when it comes to placements IIT Bombay is ahead of all. It is in bombay, the economic capital of country so the best companies visit the campus.
• IIT delhi
• IIT kanpur
• IIT Kharagpur
• IIT Madras
• IIT Hyderabad

I hope this helps. (Apart from IITs, IISc banglore is one of the bests for reasearch work)