Even when she's crafting hits for other people, there's a vulnerability in Sia's songwriting that rings true. On This Is Acting, she sings some of the songs she wrote for -- and were rejected by -- stars such as Adele, Rihanna, and Katy Perry. Though they were intended for other singers, Sia sounds as commanding and genuine as ever. "Alive," which she co-wrote with Adele, has an empowering sweep that Sia takes in a direction that is all hers, while "Bird Set Free" is both intimate and anthemic, a territory of which she is the queen. ~ Heather Phares