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 really liked BLAME! if you like cold, alien anime about people in a decaying concrete world.
Edit: manga* I don't know why I said anime. Got anime on the brain (always).
Ooooooh, that art is looking SICK
I love the premise of being lost in an impossibly large decaying city. House of Leaves vibes
seconded, BLAME! is a very thought provoking comic.
Definitely gonna check it out