I would advise you to pursue PhD from IISc Bangalore over IIT Roorkee. IITs are mostly inclined towards the theoretical aspects of Research in Science and Engineering, whereas, IISc Bangalore works on the in depth research and practical aspects of Engineering. IISc has excellent infrastructure, faculty and research facilities besides having an excellent research potential and employer outlook for PhD Graduates. Being a Doctoral Student from IISc Bangalore is itself a matter of grace, with eminent Alumini across the world in Research and Academia.

For more information about PhD in IISc Bangalore do follow the link below

https://www.careers360.com/university/indian-institute-of-science-bangalore