I don't like to compare composers of different times using blanket statements. The Indian film industry has a rich history of brilliant composers, each with their own unique strengths and contributions. ARR is another in a series of brilliant composers. Is he THE best ever? I can't really answer that. Is he THE best to me? Sure!
What if RD Burman, Madan Mohan, Naushaad, or even Illayaraja etc. had been alive today with their same talents but with the luxury of sound technology and computers. Would their music also reach across globally? Would love to hear your thoughts. As far as I'm concerned, nobody has EVER combined different genres of world music more beautifully than our ARR. How does ARR compare to other composers in the past just in terms of pure melody? Originality? Please please please do not turn this discussion into a "Illayaraja is way better than Rahman" or "RD Burman is nothing compared to AR Rahman" type of warfare. I'm just curious to know your thoughts about the above.