Won't life be boring if we only worship and listen to Yuki Kajiura? But I love to answer this kind of question.
My fave musicians are (in alphabetical order) :
-Anthony and The Johnsons
chamber music. "hope there is someone", "bird girl"
Why? because of his ability to turn sadness and pain into a music. And his deep voice of course.
-Arcade Fire
Canadian baroque, alternative band. "No cars go", "intervention", "Haiti"
Why? They sound very nostalgic, country, and makes me remember of the world melancholically. And their use of instrument into the genre. Harpsichord, Church Organ, etc , etc.
-Archive
Trip hop, electronica collective from England. "Again", "Fuck U"
Why? Simply trippy, dark and melancholic.
-Björk
Electronica, Experimental, Ambient queen of uniqueness and queerness. "Joga", "Bachelorette", "All is full of Love", "It's oh so quiet"
Why? hm... It is quite difficult. She is able to make music out of strange noises and sounds. She is very artistic and talented. Musically, it is experimental and strange, makes you wonder of alien worlds.
-Clint Mansell
Acclaimed Movie Soundtrack Composer. Musically very ambient and dark. "Lux Aeterna", "Death is road to awe", "Welcome to Lunar Industry"
Why? Again, Trippy, Dark, Melancholic. His musics have a mixture of classic and modern.
-Madonna
You don't know her? "Like A Virgin", "Like A Prayer", "Hung Up", "Music", "Ray of Light" etc etc.
Why? Well... I like her for her different genres.
-Massive Attack
The father of trip hop and bristol sound. "Tear Drop", "Unfinished Sympathy", "Angel", "Paradise Circus"
Why? God, i have to say it again... trippy, dark, and melancholic. As the founder of this genre Trip Hop of course I love the band.
-Portishead
The mother of trip hop? "Glory Box", "The Rip", "Only You"
Why? They sound very industrial, and again, dark and melancholic.
-Susumu hirasawa
Asian Cyber-techno. "Byakkoya", "Parade"
Why? It is about the same as björk. But each of his album doesn't really have uniqueness like Björk's.
-Unkle
another trip hop band, well musically more accessible and light. "Broken", "Lonely Soul"
Why? ... hmm... sam reason as trip hop genre.
-Yasunori Mutisuda
JRPG composer, famous for his celtic influenced musics. "Graf", "Small Two Of Pieces", "Pain"
Why? His musics are simply heavy.