As Prime Minister Modi is on the hit-list of many, one would expect him to take his own security very seriously. And he is expected to travel a lot more than previous Prime Minister.
From that point of view, he would have to choose his official ride. But as an advertisement for his nationalism, he may want to utilize this opportunity and opt for one of the Indian-made armoured limousines, provided that they offer similar or better protection features.
Hence, the question really boils down to which Indian car manufacturer can match the security features of the sort of vehicles that are commonly used by a preponderance of foreign heads of state.
Your vote: Armoured Jaguar XJ Sentinel (Used by UK PM, and built by what is now a subsidiary of TATA Motors)