Mattman and Robin are a good producer/songwriting duo to add. Also Julia Michaels and Justin Tranter. They all wrote the majority of Selena and Gwen's new albums and songs from 1989, Queen of the Clouds, Emotion, etc
EDIT: ooh also Alex Da Kid. He produced a TON of rap/pop smashes early this decade. LTWYL, Airplanes, Radioactive, etc. He also happens to be the producer of 2 of my faves

(Imagine Dragons and Skylar Grey)