Björk is great! One of my all-time favourites. Although I can understand people that find her annoying. Her childish voice and extreme extravagance are not everybody's cup of tea. She's definitely extremely innovative.
Vespertine is probably also my favourite Björk album, with Post being second. Hyperballad is such a great song. Medùlla is a great experiment although hard to bear with at times. I didn't like Volta much at first, but it's slowly growing on me.
Selmasongs, the soundtrack to Dancer in the Dark, is also overwhelming. I have it since years but I watched the movie only recently. It is a great movie but completely merciless with the audience. And after watching it, listening to the music alone is even more intense.