48. 5 Seconds of Summer, '5 Seconds of Summer' (2014)
With their self-titled debut, 5 Seconds of Summer presented themselves as the perfect marriage of boy band and rock group – accomplishing what so many pop-punk acts always seemed to aspire to, but could never quite realize. Lead single and wide-eyed, pheromone-heavy teen anthem "She Looks So Perfect" sums up the Aussie quartet's shrewd One Direction–meets–All Time Low blend. Think of 5SOS as the more politically-correct children of Blink-182, and one of the few acts on this list writing about high-school woes ("Good Girls," "Social Casualty," "End Up Here," virtually every other track on 5 Seconds of Summer) from an authentically adolescent perspective. Their youthful abandon centers around saccharine-sweet melodies, four-part harmonies and, of course, dreamy locks: As lead guitarist Michael Clifford joked with latter-day pop-punk self-awareness in the band's Rolling Stone cover story, "Let's face it, half of pop-punk is just about the hair." M.S.