For IR..who is undoubtedly king of bgm..there are many to list..so let us focus on the others. People say YSR is better than ARR in this area..but i feel YSR's bgm is just a mix of both...we got to give credit to ARR for introducing a new style of BGM also..using keyboard sounds or at times natural sounds. If IR managed to bring out the emotions and beauty of the scene ARR managed to give the scene a robust and energetic effect. Most notably....Kannathil Muthamittal(A idea of how keyboard sounds can sound so pathos like), Minsara Kanavu (He has used some orchestraic pieces in the songs and parts as well), Mudhalvan( The bgm makes the movie even more peppier and heroistic feel), Indian ( He used a theme for the indian thatta that HJ sort of modified it to use for the Anniyan theme(not stranger in black)),Alaipayudhey(His forte..romantic bgms) Another unnoticed personality is VA..i notice he loves to use minisongs as BGM in dishoom..and by2 had a forest like background score...not so polished..but very effective as well(VA stands for vijay antony) Karthik raja...he is a offset of IR but it really is nice to hear his BGMs...dum dum dum,album and naalai had some fantastic background scores.