Probably Marina and the Diamonds - Electra Heart
Upon first listen to some of her songs, she just seemed to be some enjoyable, decent pop. But as I listened to Electra Heart all the way through, and then started watching the music videos in sequence, I started to grasp the concept of the album, which is an interesting one. The combination of the concept, her lyrics, and the diversity of song styles results in one of my favorite albums in quite some time. She's incredibly talented - plus she plays piano and does acoustic versions of her songs. One of those rare pop singers who's a real musician.