I am a total newcomer to Hop Along but their sound is great. I like that it's not quite like any one of the genres listed on their Wikipedia page but a mysterious soup that contains elements of each of those genres, the tempo of punk, emo vocals, power pop guitar sound.
The lead vocalist, Frances Quinlan, has incredible control of her voice and opts to create melodies that employ more than a few styles within a verse or chorus. She can alternate between straightforward singing, strained vocalization, and speech-singing.
Really great record. Would love to go back in their discography and see how their unique sound evolved.