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'm not even joking, that's an actual thing that happens towards the end of IIRC volume 12, it just stops the story completely to talk about that and then follows it up with what is basically "and fuck the Japanese government for putting refugees in inhumane camps and having fucked up racist immigration laws, btw two of the characters go on to become international human rights advocates working for the UN in subsequent decades," because writing these random epilogues about characters going on to be great people is also a frequent thing it does, like it making some creepy little sexpest kid in the earlier chapters go on (50 years later) to be a prominent judge with an unshakeable moral compass because of how good and merciful the protagonist was towards him that one time.
It's absolutely unhinged and I don't know whether to be impressed or disgusted by it.
Kinda reminds of a sequence in the middle of Animal Man where the story kind of just stops dead and the author looks to the reader and says "slaughtering dolphins is bad"