Starting with some classics that I still love listening to:

Detective Conan: Koi wa Thrill Shock Suspense

Of Ranma 1/2 and Kamikaze Kaitou Jeanne I actually only like the German OPs (mostly because of nostalgia), but the melody is the same as the Japanese ones. Ranma 1/2 OP: German / Japanese

Kamikaze Kaitou Jeanne OP: German / Japanese

I still listen to quite a bunch of old Anime songs, but the 3 above are probably my favourites.

I like all the Demon Slayer OPs and EDs, but this is by far my favourite: Kizuna no Kiseki

Oshi no Ko OP: YOASOBI

and the Ending: Mephisto

The anime was kinda shit, but I love the OP of Youkai Apartment Complex: Good Night Mare

And because I love cute shit, the OP of My Love Story: Answer

And this one isn't an OP or ED, but a song played during the movie, but I love Grand Escape, from Wheathering With You.