My vote goes for Ilaya Raja saab, here is a nice article comparing them...
Music makes merry. That too when backed up by film industry. The charisma of the film music is often influenced by many artists. Two of such greats are Mr.Ilayaraja and Mr.A.R.Rehman (both from Tamil Nadu). TN always had its perennial classical musicians and audience but slowly in mid 50s, a bend was silently rowing the boat towards film music. There came Mr.M.S.Viswanathan and Mr.Ramamoorthy(V & R), divulging the variety behind music and the musicians. Though V & R produced many beauties to list their assets, classical music was their main material. They were reluctant to use some of the western instruments. This scenario was crowning for nearly three decades. Finally, Raja made it to the surface, with his thunderous blockbuster, "Annakkili". In the year 1976, amidst blooming MGRs and Sivajis, Annakkili turned to be the greatest hit signaling signs of something unusual to the centering.
V & R were thoroughly out of the blue of Raja's entry. Their market soon underwent an onslaught. Raja, also was accused by some of the greats like TMS (Mr.T.M.Soundarrajan) for trespassing the limitations of film music. He not only had to prove his worth but also had to thrive the criticisms of his predecessors, which he managed well. Ultimately the situation succumbed the fame of Raja. He started hitting screens with great frequency. Within five years he had accomplished almost hundred films, out of which around fifteen were silver jubilee. He powered the industry with his amazing compositions. Often critiqued of providing only folk music, he contended well in his own style. Wanted to prove his worth in western music he disclosed some gems like "ilaya nila" etc etc. The lights of greatest directors and artists like Rajiniknth, Manirathnam, Balachander, Balumahendra, Fazil, Bharathiraja were all ignited by Raja.
In spite of the songs rendered, Raja was purely astonishing in his back ground scores. The BGMs are even acknowledged today with same admiration it got during their release. Most of such BGMs ringers in almost 70% of the modern mobile phones in TN. Till mid 90s it was Raja, having his tenure in film music. There entered the cyclone, cheering the industry with freshness and prosperity, A.R.Rehman. Getting his entitlement (IsaiPuyal) within ten films, he mastered the use of keyboard and percussion instruments.
He occupied the crease, with his class music and his abilities of sound engineering. Soon the frequency of Raja was declining though the quality of his music remained spirited. Meanwhile ARR reached great heights with "Vande Mataram" and "Bombay Dreams". Like Raja, ARR also brought out some big talents like Shankar and Rajiv Menon. Apparently, he captured almost all the big clients of Raja, starting from Maniratnam to Kathir. But, the freshness of all his compositions sustained only for a short span of time. He was frequently picked apart for the same reason. Even when he was holding the market, he couldn't deliver as consistently as Raja did, lacking also in numbers. But the market valued him very high, ultimately satisfying his business. Raja's top salary marked 25 lakh for Thalapathi, whereas ARR bested him almost in every film he did.
Raja still came out with some excellent hits like Kaadhalukku Mariyadhai, Heyram etc. Over today's trend, the freshness which ARR delivered, through which he outlasted, is being commanded by every music director. But the winkling music of Raja, which gold plated the creations and creators is everlasting. Every youngster is even humming songs of early 80s and are amusing with hits of Raja. ARR who was proclaimed as the new cyclone, lasted only for 9 scale years. ARR delivered his best only with worthwhile directors. Raja outlasted with almost every director he worked with. Moreover, film music is not only meant for commerce but should also target audience. Success is a journey and not a destination. Seems that ARR had lost his touch and crew but still Raja is coming out like Kasi and Virumandi.
Western music always has the glamour but the music of the land holds the beauty. Raja on that perspective, undoubtedly stands apart among all music directors(including ARR). "Vande Mataram" and "Bombay Dreams" are our pride but "How to name it" and "Nothing but wind" are our soul.