Delacey may be a born-and-bred SoCal kid, but her break came when she wrote an unrequited-love letter to the East Coast. A melancholic murmur that builds to a colossal drop, “New York City” (which was scooped up by The Chainsmokers for 2015’s Bouquet) is a trademark tune: restrained heartbreak set to a pulsating beat. The millennial songwriter has parlayed those deft anthems about bad romance into hits for Halsey, Demi Lovato and Zara Larsson.