Adachi and shimamura is one of my all times fav romance ones!

I totally recommend mangas by Usumaru Furuya, especially The Music of Marie and Palepoli (little warning on Palepoli though bc it contains adult content and some mature themes -even the Music of Marie treats complex themes but there aren't as many scenes depicting "sensible topics"-). I've recently started buying mangas/graphic novels published by Coconino press and ngl most of them are pretty valid (although idk if Coconino publishes even outside of Italy). Poor Little Mina is also quite nice, even though it isn't really my genre.

Other than that, some other really nice mangas are Berserk, jjba, Goodnight PunPun (I've only read the 1st volume bc I can't find the others anywhere), Junji Ito's stuff etc. etc. (most of you have already read these probably).