Hello,
Undoubtedly IIT Guwahati is a better among the three IITs because it is considered to be among the top 7-8 IITs. So, the cut off for cse branch IIT Guwahati is also under 600-700 so you need to score really good to get the cse branch over there.
The infrastructure and view of IIT Guwahati is just amazing you will enjoy the campus life. I can be rest assured of that.
But the other IITs are not so good with computer science branch and are not considered to be among the top ones. IIT Patna is comparatively a newer IIT.
If you want to check the other colleges that you can get ,you can take the help of college predictor link given below -
https://engineering.careers360.com/jee-advanced-college-predictor?utm_source=qna&utm_medium=jee_adv_cp
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