What's your favorite anime song? [GA included]

I couldn't read the name of half the songs so I gave up.
Choosing a single favorite song is almost imposible, so I will just name 3 that I love but I might have forgotten another one worth mentioning.

Butter-fly - Digimon
Sh0ut - Re:Creators
Sincerely - Violet Evergarden

up

Hey.
I recommend this anime song to you, I like it.

Hello, ni hao ma.
https://www.youtube.com/watch?v=Ira-ky7BeDo

bump

There are many great songs, it was hard to choose at the end. I was surprised that Cruel Anghel's Thesis did not make it to the list. And Guren no Yumiya, though it's full version is not as good as the short OP sequence IMO. It came down to "Yui - Again" as a winner, "LiSA- Oath Sign" being a close second. LiSA dominated the final quarterfinals though.
As for my absolute or current favourite, its even harder to choose. You've included Hishoku no Sora, which is around the closest, kind of an "evergreen" for me.
To add to the topic at hand, I'll simply leave some japanese songs that are good in my opinion. Enjoy!
Scandal - Everybody Say Yeah
MAN WITH A MISSION - My Hero
Konomi Suzuki n' Kiba of Akiba - Watashi ga Motenai no wa Dou Kangaete mo Omaera ga
Yoshiki - Red Swan
Angela - Beautiful Fighter
Mitsunori Ikeda feat Aimee-B - Fallen Angel
Hanatan - Tengaku
ShibayanRecords - Fall In The Dark

I'll be going through the comments.
The anime songs proposed would be added, if I can find official video on youtube.

These songs are aleady added：
K RETURN OF KINGS「アシンメトリー」
K「KINGS」
ハンドレッド「TABOOLESS」
灼眼のシャナ「JOINT」
灼眼のシャナ「ONE」
天上天下「Bomb A Head! V」
GUILTY CROWN「Euterpe」
青の祓魔師「CORE PRIDE」
とある魔術の禁書目録「See visionS」

First Opening for FMA Brotherhood
https://youtu.be/JzUBwwJF4JU

Thank you! Happy Holidays!
I don't forgot names but it were 2 songs. First one is opening for Black Lagoon and another is guitar-girl song in Angel Beats. Author of the second one should be Kishida Kyoudan & The Akeboshi Rockets if I remember truly.

1st favorite
2nd favorite
3rd favorite

I love this one https://www.youtube.com/watch?v=2ZN-zAKIfyQ

added these songs：

ハイキュー!!「イマジネーション」
昭和元禄落語心中「薄ら氷心中」
クロスアンジュ 天使と竜の輪舞「禁断のレジスタンス」

Akeboshi - Wind (Naruto)
CHA-LA HEAD CHA-LA (DBZ)
Aqua Timez - Alones (Bleach)
SID - Ranbu no Melody (Bleach)
FLOW - Colors (Code Geass)
SPLAY - Drawing Days (Katekyo Hitman Reborn!)

added these songs：

機動戦士ガンダム 鉄血のオルフェンズ「Raise your flag」
CROSS GAME「Summer rain」
狼と香辛料「旅の途中」
∀ガンダム「Moon」
攻殻機動隊 S.A.C. 2nd GIG「torukia」
蟲師「The Sore Feet Song」
ef - a tale of memories.「euphoric field」
CITY HUNTER「SARA」
「Theme for Panty & Stocking」
空の境界「ARIA」
空の境界「fairytale」
空の境界「傷跡」
空の境界「oblivious」
空の境界「sprinter」
STEINS;GATE「Hacking to the Gate」
Serial experiments lain「DUVET」
Ergo Proxy「kiri 」

Anime bump

Thanks for the train and happy new year. Here're some old favourite of mine:

TM Network - Get Wild
Hitomi - I Am
Shin Hurricane Polymar
L'Arc en Ciel - Driver's High

There are so many good anime songs out there, it is very difficult to name a "favorite." Still, there are some songs that "stay" with me.

Happen -Kogarashi ni Fukarete-
My Soul, Your Beats
Crossing Field

...and pretty much everything in the Sekirei soundtrack. (I think there's only one song out of both seasons that I didn't like.)

I'm not sure if it's on your list, but here is the one that comes to my mind:
https://youtu.be/EJYKsY0Vcts

added these songs：

MURDER PRINCESS「ヒカリサスホウ」
SOUL EATER「Style.」
貧乏神が!「Make My Day!」
XXXHOLiC「19才」
Fate/stay night「disillusion」
パンティ&ストッキングwithガーターベルト「D City Rock」
パンティ&ストッキングwithガーターベルト「Fly Away」
FLCL「Ride on shooting star」
CITY HUNTER「Get Wild」
新機動戦記ガンダムW「JUST COMMUNICATION」
秒速5センチメートルOne more time, One more chance
攻殻機動隊「living inside the shell」
あたしンち「さらば」

I knew instantly I saw it that 'The Cruel Angel's Thesis' would come out on top in the test for me. Great and still so memorable tune that I have to listen to in full when it plays somewhere randomly.

Other really good songs that come to mind immediately when asked about anime songs (regardless of if I like the anime itself or not):
Ali Project - Kinjirareta Asobi(Rozen Maiden)
Asa-chang & Junray - Hana (Aku no Hana)
Ayumi Miyazaki - Brave Heart (Digimon)
Eiko Shimamiya - Higurashi no Naku Koro ni (Higurashi no Naku Koro ni)
Koji Wada - Butter-Fly (Digimon)
Linked Horizon - Guren no Yumiya (Shingeki no Kyojin)
The Neutral - Nichiyoubi no Taiyou(Narutaru)
Nightmare - The World(Death Note)
On/Off - Futatsu no Kodou to Akai Tsumi (Vampire Knight)
SCREEN mode - Dive (Musaigen no Phantom World)
Shimamoto Sumi - Ai Just on my Love (Majutsushi Orphen)
Takayuki Miyauchi - Nagareboshi Gin (Ginga Nagareboshi Gin)
Yasushi Ishii - Logos naki World(Hellsing)
Yousei Teikoku - Kuusou Mesorogiwi(Mirai Nikki)
Yui Horie - Scramble(School Rumble)

My fav is the Kokkoku Opening Flashback https://www.youtube.com/watch?v=g60Mz5ZQdPs

Getsumei Fuuei (closing credits song - 12 Kingdoms)
https://www.youtube.com/watch?v=fEmcQN2NHD4

Aimer LIVE Ref:rain / Koi wa Ameagari no You ni OP / Orchestra
https://www.youtube.com/watch?v=cRD6NikS6Rs

BUMPITY BUMP!
Thanks for the ride.