Many of my picks were already mentioned! I truly think Yoshihiro Togashi is not only a master but a genius. I love Inio Asano, Junji Ito, Takehiko Inoue (Vagabond is amazing and one of my favorite things, but I can't choose between it and Slam Dunk because it's the best-paced comic I've ever read, it's amazing), Naoki Urasawa (20th Century Boys is probably my favorite manga yet) and I love love LOVE Ai Yazawa. Nana is my jam.
Some of my favorites that weren't mentioned yet:
Akira ToriyamaI went through a pretentious teenager phase where I thought DBZ was garbage. It was when I read the manga, years later, that I truly started to appreciate how great Toriyama is. His pacing is killer, his fight choreography is spot on, his angle choice is amazing and he ALWAYS ends the chapter with the perfect cliffhanger. A true master. Also, Sandland is the shit.
Tite KuboOk, hear me out.
I love Kubo's art. Among his contemporaries, I think only D.Gray-Man's Katsura Hoshino could match him in aesthetics. His line is just drop dead gorgeous. But I feel Kubo has a different narrative style from his other Jump companions. He has this really unique mix of cinematographic and subtlety that can be really cool if you allow yourself to give the benefit of the doubt, especially in its last half. His last two arcs flirt more with seinen than shonen sometimes and can be so weird. Man I miss Bleach so much!!
Masami TsudaI just love Karekano too much. That's all.
Also, shout out to Kyoko Okazaki. Only read one manga by her, since there are no other publications here, but damn, Helter Skelter is straight up masterpiece territory.