All great Music Producers have their own sound. Instantly recognizable no matter who they are producing. Quincy Jones had that touch. But it took awhile to achieve it. Before his breakthrough solo album, Body Heat in 1974, Jones was an arranger, composer, producer. of mostly Jazz & Jazz Vocalists. It wasn't all serious work. He produced Lesley Gore's classic from 1963, "It's My Party", a #1 record. With Body Heat that changed. He was squarely courting the mainstream R&B charts. And it worked. The album was a success. Jones began producing other R&B accts. Brothers Johnson, Rufus w/Chaka Khan, Donna Summer and George Benson. Of course there was Off The Wall, the album that defined the Quincy Jones sound for all those acts and more that I mentioned. So, while "Rock With You" is the definitive Q sound, I would put my weight around George Benson's 1980 hit "Give Me The Night" as his best single.
Regardless, the success of Off The Wall and Thriller let Quincy do whatever he wanted in the 80's. Solo albums, "We Are The World", movie soundtracks. But it all comes back to those early 70's productions. It's where he developed his sound. No one could duplicate it. All Music Producers have their own sound indeed.