I have two favorite manga artist/creators. Both are almost completely unknown :-) But, both have a simplistic, clean style. They rarely use screentones, just rely on their inks. And both tell amazingly funny stories. We seldom see this kind of manga outside of Japan because the people who license stuff think everything should look like Kanan's art... fully rendered, covered with screentones, etc. But most Japanese manga is the more simplistic kind.
First, Yo*censored*oh Asari. His main life's work has been the manga, Lucu Lucu (though he did design most of the angels for Evangelion). His art is simplistic, he's not trying to impress anyone, he draws to tell his story. Which is amazingly funny and well done. Lucu Lucu is the greatest unknown (in the western world) manga ever drawn

The second creator is Coharu Sakuraba. She's the creator/artist/writer of Today In Class 5-2 and Minami-ke. Again, very simple artwork to compliment great storytelling and humor. I love how she can switch from simplistic gag manga still to fully rendered western art faces to make a joke.
