Not the best but certainly memorable and well fitting (if a bit repetitive) is Black Bullets.
Granted there are plenty of other anime with amazing soundtracks that for the most part upon hearing it you know what it's from.
Berserk (1990's Version) and Bleach come to my mind anyway (Don't know if you'd call Bleach's soundtrack amazing, but I would say memorable at least)
There are many others I could name, anything by Hayao Miyazaki has an absolutely amazing musical score to it.
I usually like older animes, but a friend of mine recommended Made in Abyss and I have been binge watching it as of late.
I had my reservations about it, but the soundtrack is probably one of the most beautiful things I've heard in a while.
And of course, a classic, Ghost in the Shell. I don't think there's an anime out there that's been able to top this in my opinion. I get chills whenever I hear any of Kenji Kawai's pieces.