By far, my favorite manga creator is Shimura Takako. By no means is her work for everyone, and most anime fans won't like her writing, but dammit is she an amazing writer!
Shimura Takako is most famous for writing Aoi Hana, a lesbian schoolgirl romance, and Hourou Musuko,which addresses transgender and transsexual issues. She does something that is extremely rare in manga; she writes about LGBT topics in a way that is mature and realistic.
Although genderbending, crossdressing and homosexuality are things that show up in manga a lot, even mainstream manga, it is rarely handled in a mature fashion. Yaoi rarely goes beyond gay porn and into actual issues of sexuality, as the characters exist in a fantasy realm of rainbows and puppies where everyone is attracted to males, but not gay (It's not uncommon for a character to say, "I'm not gay! I just like so-and-so!") and very little of it is written for actual gay men. Also, the people in the relationships in yaoi alway fall into certain roles, as if the writers of yaoi can't imagine a relationship that doesn't follow a stereotypical straight relationship, and rarely reaches outside of those compartments they place their characters in. Yuri seems to attract actual lesbian readers more often than yaoi does for gay men, but it often tends to be just as formulaic as yaoi.. Alternate sexualities show up more often in anime, particularly when geared towards younger readers, than they do in American media, but they aren't very accurate or even very positive portrayals.
The works of Shimura Takako are the exception. Never pornographic, yet not shying away from the issues of sex, particularly in young people, her manga rarely feels like manga, and more like a well-written young adult LGBT novel. Her artwork is very traditional and watercolored, and very beautiful. However, most people that are into anime won't like this series. Her pacing is extremely slow, and her works can be confusing, because they often have really big casts and sometimes the side characters are hard to remember ( I had this problem more with Aoi Hana than with Hourou Musuko. The side characters in Aoi Hana aren't as interesting in my opinion and kind of blend together). She also deals with subjects rarely addressed, which can make some people uncomfortable. I gravitate towards the series that are often unknown or forgotten, and the works of Shimura Takako need much more love, for tackling the issues that most people shy away from.