20. Camila Cabello + Shawn Mendes 'Señorita' Not a collaboration anyone was begging for, but this coming together of a boy and a girl - one straight, one probably not, both hungry for fame and happy to market their fairytale romance to any paparazzo on the Getty Images payroll - instantly exploded to become the biggest pop single of 2019. And you know what? Unlike most years when a song claims that title, Señorita kind of deserves it. This is an effortlessly melodic slice of breezy, guitar-driven latin-pop that fulfils its brief of being sexy while still being just PG enough for little Becky to sing every word when it comes on the radio. That's actually not shade. Every part of this song, be it the verses or the chorus they flow so freely into, is a hook. Extra props for the fact that Shawn also sings the "I love it when you call me señorita" line underneath Camila's vocal. I'm sure he does.