I heard "McArthur Park" was an attempt to see if a really dumb song could be made into a hit with a good tune and a star performing the song.
They succeeded I guess.
Donna Summer's husband Bruce Sudano co-wrote two great #1 songs of the late 1990's:
"That's the Way It's Meant to Be"
"A Different Road" (Donna has covered that song recently.)
But as for singers with quality?

Now that's a singer.