Openings and soundtracks that marked your life...

[chicholiriko]

Mines are:

Asterisk - Orange Range
Rolling Stars - Yui
Haruka Kanata - UNLIMITS

Yep, I know those are from Bleach, but it's my favorite anime, so... I have more, but those 3 were the ones that really help me when I was going thru some hard times in my life.

[Gexis]

Pokemon: The First Movie Original Motion Picture Score
https://www.youtube.com/playlist?lis...4AF8A743E42AB6

[WalterWhiten]

Blue bird from Naruto is amazing.
I also like Hunter x Hunter - To give a Marionette life.
These are two of my all time favourites but I have so much more that I like, I used to only listen to anime Ost

[-WhiteBeard]

Stand up be strong from bleach

[NICHIKA]

HAVING S*X WITH THE BEES AND THE EAGLES

[lainchan]

Serial Experiments Lain - OP
Welcome to the NHK - Hitori no Tame no Lullaby (OST)
City Hunter - The Shining of Cat's Eye (OST)

I've come back to these 3 and listened to them hundreds of times. If you haven't heard of any of them, I'd recommend listening to them and watching the anime. All amazing anime.

[infosubject]

For me it is AoT Sasageyo XD

[scotbud123]

There are too many good ones to list...so I'll just list series I think have banger openings/soundtracks and stuck with me the most.

Naruto
Black Clover
Bleach
Boku no Hero
Gurren Lagann
Attack on Titan
Hunter X Hunter
Sword Art Online (we're just talking about music here, remember)
Angel Beats
Kill La Kill
Jojo's
Yu-Gi-Oh
Pokemon

And some that are shorter/newer but still good:

Dr. Stone
Jujutsu Kaisen
Fire Force (first opening in particular)

The three in bold/at the top might be the best/most impactful though.