That SPB was a singer unparalleled is a fact. It's rare for singers to maintain their voice as they age. But it seems SPB was ageing like wine, becoming more sweeter with age. He was able to perform live as recently as a few months ago with the same intensity in voice as he would have done 30 years ago.
There will be singers who might be having more knowledge about music and might be well trained but no one can be ahead of him, they can be equal to him, when it comes to understanding the lyric and the emotion behind it and then conveying it to the listener. He always stressed that a non native singer singing in other language is not a problem as long as they try to understand the meaning and correct pronunciation of each word. But now a days it has become a fashion to get the songs sung by those who don't know the meaning of the song nor the pronunciation of words. So many times they break words where they shouldn't because they are concentrating on the musical aspect leaving aside the lyrical part and the emotion part. The output is a good song with good music but one which may not survive the time, because the emotion isn't there. The reason he ruled Tamil and Kannada film industry apart from Telugu, which anyway was his mother tongue, in spite of being a non native singer is because he put the effort to learn and understand the languages he had to sing.
Then the role he played over the last two decades hosting talent shows and nurturing new talent both in Telugu (Paduta Teeyaga) and Kannada. I am not sure if he was hosting any such Tamil talent show. The shows are a breath of fresh air in these days of manufactured emotions and acting. There are no fake fights between judges, no harsh criticisms and overacting for TRP's, just pure music. If he has to correct someone, it would be one word of correction mingled with 10 words of praise, thereby letting them know the mistake without hurting them. Zee Saregamapa was like that in 90's when great people like Pandit Jasraj etc were judges. So many singers have come from his shows who made a name for themselves. Hemachandra, Karunya (Indian Idol Finalist), Sriram (Indian Idol Winner) and many more. His show was the only singing talent show I ever watched.
Apart from that there are other attributes of his which endeared him to many. His humility for one. And this wasn't something he enacted for media, this was natural for him. I could give so many incidents which would throw light on this great human being.
The below one gives the glimpse of the person he was, because there was no media to see, no need for him to do what he did.
And then after being himself one of the greatest singers and after attaining huge fame, he didn't have any qualms to accept the greatness in others. It is said that only those who are secure in their strengths and standing can accept and acknowledge the greatness in others. During the current times, where everyone with even some success seem to have huge ego's, especially in the film industry, the way he gets along with his co-singers, be it a newcomer or a veteran, with respect is really a lesson for all.
Also while many, especially non-Telugu speaking fans of his might know his work in combination of Ilayaraja, I think those songs wouldn't be beyond 2 or 3000. Given his vast body of work, there are thousands of gems with others, like MS Viswanathan, KV Mahadevan, Hamsalekha, Rajan Nagendra, Keeravani, Chakravarthi, Ramesh Naidu to name a few. Most importantly he was not only a singer but a music director as well, having given music for around 50 odd films.
A melodious sample from one of the films for which he worked as music director as well.
I could go on but don't want to spam this forum, for there is a lot one can say about such a great artiste and human being.