IMO a perfect pop song has to be seamless. The genre is irrelevant whether its rock/country or R&B biased.
1960’s California Dreaming
1970’s Dancing Queen
1980’s Billie Jean
1990’s The Thunder Rolls
I would have to do some more research to give my best examples from 2000’s 2010’s, completely stopped listening to Top 40 music when the Boy Band craze hit. Only new music I listened to after that was Metal/ Alternative Metal and later Indie Rock.