It's a good question. I wonder if anyone really knows the answer. Two guesses off the top of my mine: The Look of Love and What The World Needs Now Is Love.
Most recorded song?
Probably WTWN NOW or Alfie.......I remember Alfie had quite a few recordings on it at the time...Tony Bennett, Andy Williams. etc...
I can only imagine that people like Carmen McCrea, Jack Jones,
Eddie Fisher, all the single vocalists...male and female made recordings of it..same with WTWNN..These 2 songs became modern standards, and have universal appeal...despite the unusual melodic intervals and time feel of "Alfie"...Even though it was somewhat short lived..."Raindrops" had quite a few recordings at the time also...
By the way, one of the most recorded songs in history is Yesterday...(Beatles)
Paul McCartney who wrote the song, kidded with TV interviewer Charlie Rose, when Rose mentioned it, and said "yeah it did quite well".....to which the audience roared with laughter(after Paul's understatement)Paul quickly then chuckled himself realizing the absurdity of his under-statement and the audience's reaction...it's a great moment on video tape...
Some years ago (at least ten), an italian magazine reported that the most covered sond of the world was "Raindrops keep fallin' on my Head". It was estimated that existed about 10000 versions of that song and that had been transated in quite all languages. The italian title for example is "Gocce di pioggia"
that would be quite a record collection collecting all of the raindrops and yesterdays..........
enough to fill a large room, and probably a life time to collect them!