While I have only heard Palghat Mani only on tapes ,no doubt his playing is divine and matched only by his son ,Rajamani who is not a regular concert player.
Others who immediately come to mind are Sivaraman,Trichi Sankaran,Karaikudi Mani,Palani Subbudu who should rate as top class.As accompanist Vellore Ramabhadran ranks high on soukhyam.