Choosing between IIT KGP Electrical, IIT Madras Mechanical or IIT Indore CS should depend on your area of interest, career goals, and preference. All of the IITs offer excellent academic structure which helps to enhance both your theoretical and practical skills.
In today’s modern era, there is more scope in CS than any other branch followed by Electrical. In fact, both are quite similar in some aspects.
However, if you are a physics lover, CS may not be the right choice for you. It is core engineering that contains applied physics, along with many transferable skills. EE has the most elaborate Physics followed by ME which has always been more intuitively accessible. Concerts covered in these are Force, mass, deformation, vibrations, elasticity and plasticity in 2D and 3D, stress, design, heat, thermodynamics, etc
EE is closer to technologies that are in higher demand these days while energy and water are very much ME topics.
IIT KGP and IIT Madras seem to be the best options for you. Choose the one that will give you a branch of your choice.