Been reading it lately, and it helps reduce my scrolling time. I've hardly read any, so you can recommend really popular stuff, too.
I've read Vagabond, 20th Century Boys, Claymore (years ago), and some berserk. I just finished reading Teppu, which I thought was an interesting subversion of a lot of anime tropes. I also liked that it was a short run (only 8 volumes). I guess I like seinen, but I've also enjoyed josei like She Loves to Cook, and She Loves to Eat.
Anyway, no shonen please. Hard mode: please nothing about high school
I have been rereading Nagata Kabi's series My Lesbian Experience With Loneliness, My Solo Exchange Diary, My Alcoholic Escape From Reality, and My Wandering Warrior Existence. That and Poppy Pesuyama's Until I Love Myself
Both are autobiographical accounts of the mangaka's life. One about a queer person who felt paralyzed throughout her twenties due to not understanding who she was or being willing to pursue it. How she shook herself out of her rut, at first, but each book after that is then the subsequent issues that came with becoming a best-selling mangaka, having friends and trying to have some semblance of a "normal" life.
The other is about a non-binary mangaka coming to terms with themselves and their trauma, as well as the difficulties that came with writing an autobiographical manga and getting it published in a famous Seinien weekly. I have yet to read volume 2 or beyond, but volume 1 was good.
I've actually posted a lil review of Until I Love Myself here
I have Kabi's stuff lying around, but I haven't read it yet.
I went on a bit of a binge, and I'm a bit queered out rn