1. Chainsaw Man - Kick Back. It's the gift that keeps giving; every time that you watch it you'll find something new, and the more that you like it.
Don't get distracted by Power wearing a bikini, or the movie references - look at the details. Makima taking Denji for a walk, Denji seeing carnivorous flowers (a dangerous love), golden balls rolling... Mother's Basement does an amazing job exploring it, way better than I could.
2. Elfen Lied - Lilium. The anime aged poorly, and it's a weak adaptation of the manga, but damn! This OP is beautiful. And the Latin mass actually makes sense in the light of the manga's story:
translation of the lyrics into English
The mouth of the just will practice wisdom
and his tongue will utter judgement.
Blessed the man who endures temptation
Since, as he’s being tested, he’ll take the crown of life.
O Lord, source of virtue
O Lord, divine fire, be merciful
Oh, how holy, how serene, how kind
how lovely the virgin is believed to be.
Oh, how holy, how serene, how kind
how lovely, oh chastity lily
Switch the genders for a moment and everything falls in place: the "man" enduring temptation is Lucy, asking for forgiveness to a "chastity lily" called Kouta. And she's devoted to him almost religiously - because, even if she's a sinner, he's the one accepting her, giving her peace and serenity, pleading in her defence, as if he was her personal Virgin Mary.
3. Sorairo Days - Tengen Toppa Gurren Lagann. The song is great, don't get me wrong, but what makes the OP really special for me is that it isn't just "a single OP". The scenes shown in the opening evolve alongside the story in the anime, while keeping the same catchy song. For example, here's what the first ten seconds of the opening tells you:
up to ep8 - it's the story of three people: Kamina, Yoko, Simon.
from ep9 to ep16 - it's the story of a whole team that includes Yoko and Simon but much more people.
from ep17 to the end - it's the story of a boy growing up, Simon.
Except that it isn't just those ten seconds. It's the whole opening that evolves, throws back at earlier events just to push forward, in a way that feels completely natural and consistent with the theme of the anime series - evolving and going forward.
Huh. So... it finally occurred to me to check this. Elfen Lied and Sora no Woto share the same director -- Mamoru Kanbe / 神戸守. I probably should've figured that out sooner given that Sora no Woto's OP also references Klimt's paintings heavily, but I had no idea.
Except that it isn’t just those ten seconds. It’s the whole opening that evolves, throws back at earlier events just to push forward, in a way that feels completely natural and consistent with the theme of the anime series - evolving and going forward.
Perfect way to describe how the OP feels while watching the show. What also enhanced it for me was listening to the full version and reading the translated lyrics. I love how the second verse reveals that
Gurren Lagann Spoilers
the song is Simon sending a post-humous message to Kamina about the experiences he went through following Kamina's death: from lost and aimless to carrying on Kamina's legacy by pushing forward and cherishing every day.
It's very moving and adds a lot of depth to such an upbeat and energetic song.
You're right - and the lyrics are so well in-tune with the show that I feel a bit ashamed to not have dug a bit deeper into them, in my earlier comment.
And there's also some depth in the first part (that appears in the opening), not just the second (that you explained rather well) - how you interpret the lyrics of the first part changes, depending on the events that you've seen already.
Gurren Lagann spoilers
Before Kamina's death
A boy who digs tunnels in the dark, but wants something further than that. He doesn't know the colour of the endless sky because the village is underground. Eventually, he leaves for the outside world. There's no time to lament that Yoko doesn't like him or other trivialities - they still need to chase their tomorrows. And the answer is always there because he got dreams and hopes for the future, finally living under the sky.
After Kamina's death
A boy who falls into depression after his bro dies, and wants him back. He doesn't see the endless sky, because he's hiding himself in the shadows, digging statues. But there's no time to lament Kamina's death - he still needs to lead the team to fight the beastmen. And the answer is always there because Kamina lives in Simon's heart.