For me it would be the Fullmetal Alchemist Brotherhood Opening 1
youtube(
Jhttps://www.youtube.com/watch?v=2uq34TeWEdQ&t=24s)
Just listening to it reminds me of the moment when Edward and Alphonse tried to revive their mother and how much they suffered when they weren't able to get her back and Edward lost his leg and arm and Alphonse had his soul sealed in that huge robot body. This anime is really sad. These two brothers have been through a lot. I know I haven't really finished the series yet but it's pretty interesting and has some heart warming moments.
The second opening of Fate/Zero, interpreted by Kalafina.
The love story between Kiritsugu Emiya and Irisviel von Einzbern makes me cry. For me, Irisviel is the float that prevents Kiritsugu drown in his own darkness. Definitively Zero is the best Fate story ever in my opinion and I'm not sure that exists nothing better (maybe Heaven's Feel, but I don't finish it yet).
got a couple.
YLIA has one of my favorite openings of all time and my gateway anime to explore outside of naruto and dbz, holds a special place in my heart.
another one of my favorites of all time
also some eds:
i have already spoiled myself on the whole plot, I do plan on watching one day, but it makes me sad anyways.
video may be a spoiler if you watch it, love this whole series and it was my gateway moe drug
For some reason the Wotakoi ED gives me so much nostalgia and I can't for the life of me figure out why
https://www.youtube.com/watch?v=dVVFHFOiTxw
That and Working!!!'s ED, they both give me feels. Not the most feels, but just the ones off the top of my head and ones where I can't figure out why since neither was particularly sad or left a hole in my heart
https://www.youtube.com/watch?v=bp8N8fQ1ghQ
https://www.youtube.com/watch?v=iqNyY_YL0sI makes me kinda depressed lol
Just one? lmao
Ok for OP Durarara OP2 (Complication - ROOKiEZ is PUNK'D)
ED Banana Fish ED1 (Prayer X - King Gnu)
Fr tho idk if I can finish this anime, it's too depressing
These 2 aren't OP/ED but I feel like they had to be mentioned
Kimetsu no Yaiba OST EP19 (Kamado Tanjiro no Uta)
Angel Beats OST EP3 (My Song)
I have a lot, but I'll limit myself lol
Most of the Fruits Basket songs make me emotional, especially this one:
and this one:
It's been mentioned already, but the Banana Fish ending one:
Red Swan from Attack on Titan:
And the Ouran Host Club ending makes me cry because of nostalgia (particularly the English version):