best anime soundtrack?

music in visual media allows the producers to get right into the feels more easily, there are great anime soundtracks out there but without the visual company they had they lose something, so most anime soundtracks are great for me because i have seen the anime, and they probably not gonna do it for you if you just listen to the music....

unless is yoko kanno, she is amazing..
https://www.youtube.com/watch?v=oAczwhihCyk
https://www.youtube.com/watch?v=Kyv-TKjM3o4
https://www.youtube.com/watch?v=9tLE8miP3Zw
https://www.youtube.com/watch?v=zEJW_j8bjmg
https://www.youtube.com/watch?v=bV0D38nFUhU

One Punch Man!
and Re:zero

Nowhere
Fate

the best I ever found. :3

Hellsing has good ost.

Guilty Crown
https://www.youtube.com/watch?v=FUVDtwpWgp0
https://www.youtube.com/watch?v=jx1ajgAnHmM
https://www.youtube.com/watch?v=LF11Wf5te2I

one of the best piano songs I heard was from Angel Beats
https://www.youtube.com/watch?v=zIFV8UUs1-c

Guilty Crown songs as guy said above too, plus this songs from same anime
https://www.youtube.com/watch?v=nIrYjzHAEp0 supercell - My Dearest
https://www.youtube.com/watch?v=_sVVvv6BB6c supercell - Daihinmin

then from same singer as one of the Guilty Crown songs there is also Black Rock Shoter ending, supercell - Bokura No Ashiato https://www.youtube.com/watch?v=JKN1gS1LNLI

Song from Sankarea opening, nano.RIPE - Esoragoto https://www.youtube.com/watch?v=u7dXtrC_BdE

one of the OP or ED from Sword art online, Eir Aoi - Ignite https://www.youtube.com/watch?v=mTCESSzPZSw , and then from same singer second OP from Kill la Kill, Eir Aoi - sirius https://www.youtube.com/watch?v=Z2IwwyJUerk

One Punch Man OP https://www.youtube.com/watch?v=QImBolnTVH8

No pain, No game - Nano (Btooom! OP) https://www.youtube.com/watch?v=Ig9U4I9X2g0

Just some songs that haven't been part of anime soundtrack yet like
Nevereverland - Nano https://www.youtube.com/watch?v=2eGazzxcp3I
EGOIST - All Alone With You https://www.youtube.com/watch?v=-Hq0-47hyds
Kare [ カレ ] - supercell https://www.youtube.com/watch?v=JCRrBSmDV4A

Bebop and Akira have the best ost.
Though the intro for Baccano! and the outro for Black Lagoon are really good.

EDIT: And the best of the worst, Berserk ...would be better on something like honey and clover

Cant believe there is no White Album 2

and Symphogear
https://www.youtube.com/watch?v=sDeWtgaRwaI

how about this ?
https://www.youtube.com/watch?v=b6-2P8RgT0A

https://www.youtube.com/watch?v=mJb2KmCd5eE

View attached image.

My favorites:
Sword Art Online.
Inuyasha.
Shingeki no Kyojin.

Does RWBY count as an anime? :P

fairy tail, fmab, cowboy bebop, wolfs rain, natsume yuujinchou, nodame cantibile

Grisaia no Kajitsu. It might just be because of my obsession though.

Fooly Cooly (FLCL) still has one of the best anime soundtracks in my opinion.
https://www.youtube.com/watch?v=oYzQ5QqVD-M&index=1&list=PLeRGKarlgNylWbtR52r-tYsYxFkOlTWak

No game no life - https://www.youtube.com/watch?v=TlYEDJHmokQ

Kara no Kyoukai, GitS

Fairy Tail. https://www.youtube.com/watch?v=bH1S9IY5ztk

Yu Yu Hakusho (Opening).
I believe to be "Hohoemi no bakudam - Matsuko Mawatani"

K, Tokyo Ghoul, Mahouka Koukou no Rettousei and ofc Noragami hehe

Yutaka Yamada / Donna Burke - Glassy Sky - From Tokyo Ghoul

Tokyo Ghoul Opening (Unravel)

ROW ROW FIGHT THE POWAH

Initial D anyone? D Best Selection album.
Already mentioned FLCL and Fairy Tail OSTs are also top class in their own genres.

https://www.youtube.com/watch?v=ewBOcdz29Sw

There are a lot of soundtracks that I like. So, I can't really say which is the 'best'. But yeah, I'll update my comment if I recall any more good ones.