I'll start with the album that had quite an impact on me.
Agalloch is a band that I would simply describe as Avant-garde. They combine many genres of music and create a magnificent fusion out of them all, so categorizing them is pointless.
"The Mantle" is very ambiental, perfect for listening during a rainy day, but there is also a black metal atmosphere throughout it. The acoustics are wonderful, I find them very emotional. Lots of music can amuse you, but it takes quite an album to evoke such melancholic feelings.