What's common on those four? They're all works of art with very emotional music.
My top favorite is that of A Place Further Than The Universe for personal reasons. I had a fulfilling trip shortly after watching this show for the first time. Hearing the song again/watching the show again made me very, very happy each time.
Chiisana Koi no Uta - Karakai Jouzu no Takagi-san (I haven't watched this series, but this is an incredibly famous song and this is one of my favorite versions)
Tabi no Hidarite, Saihate no Migite from Made in Abyss - sounds like such a fun series, right? Right?! But yeah, I unironically like that song and sing along in the car. Trying to not “same reason as above”.
Okami Blues from Seton Academy - another depressing sing along song that’s actually depressing.
Although I enjoy songs mainly because they sound good to me (usually because they are catchy / pop-rocky), there are some endings that stood out to me beyond just their audio:
Comedy a.k.a. Kigeki by Hoshino Gen (Spy x Family)
The visuals is essentially Anya's dream. I especially like the latter part, of them having happy, heart-warming family time.
Whenever something sad happened in the show, this ending song starts playing, elevating the feeling of sadness.
unlasting by LiSA (SAO: Alicization - War of Underworld)
Looks like major spoilers.
My Nonfiction by Kaguya-sama cast (Kaguya-sama season 3)
It tends to get overshadowed by the Chika dance, but this ending does everything well: great audio, great visuals (with the change in art style), and most of all, it's the perfect follow-up to the episode.
Sora wa Takaku Kaze wa Utau from Fate/Zero (2nd cour) -- it's a powerful song, and I think I listened to this one all the way through in every episode. Definitely one of my all time favorites.
Taiyou - Denpa-Teki na Kanojo. (This OVA is pretty obscure, I think.) Another powerful song. No visuals for most of the ending (just text credits scrolling) -- although 神戸守 (Mamoru Kanbe) listed as the director (監督) jumped out at me! No Klimt this time, but funny that I'm talking about something he worked on again already. Maybe I should go track down his other works more systematically...
Kesenai Tsumi - FMA 2003 -- I have a lot of nostalgia for this song and listened to it way too much as a teenager after my friends started introducing me to anime. The version on animethemes is a bit different from what I remember visually but the song is the same.
Wareta Ringo - Shin Sekai Yori -- I was actually thinking about posting an animepic clipped from this the other day since it popped back into my mind...
Hibari - Lord El-Melloi II Sei no Jikenbo: Rail Zeppelin Grace Note (the Fate/Zero spin-off series) -- I like both the song and the visuals (with the seasons changing)
My Pace -- Bleach ED6; I didn't much care for the filler seasons of Bleach, but the synth from this ED and the dancing characters got stuck in my head for a while.
X Jigen e Youkoso - Space Dandy. This one is memorable to me both for the "Hey, Everett..."/「ねぇ、エヴェレット」bit specifically and the general subject of the song.
Zzz - Nichijou -- both the art and song are great. There's a couple versions, but I like this first one the best.
I think back when I first watched Welcome to the NHK that song may be what made me realize that the Japanese had also adopted a planet/weekday naming convention e.g. 火星/火曜日 == Mars / Tuesday (Tiw/Tyr's day == Mars's day; more obvious in e.g. French "Mardi", etc.); 土星/土曜日 = Saturn / Saturday; etc.
Along with a classic song by the late great Ichiro Mizuki, it also portrays the henchmen as dangerous, even though our hero manages to defeat them anyway.
The song by the great Yoko Maekawa isn't the greatest, but the care in the animation and background art is far greater than typical TV anime art for that era. The little dog is very cute, but I don't think it appears in the actual story in the show.
Utsukushiki Zankoku na Sekai by Yoko Hikasa - Attack on Titan ED1. The melody is a startling contrast from the anime itself. Unlike the action packed and destructive anime, the song is gentle and pure, sad and foreboding, but with a measure of strength. Like someone (namely Mikasa, featured in the video) desperately fighting to hold on to something that will inevitably escape their grasp.