Responses
I'll say Jin Takemiya; most of her GL manga are actually good so, you might want to scroll through them to see which of her stories click with you. There's also Milk Morinaga like 'Girlfriends', Saburouta, sorry for misspelled name to this mangaka; there is a Thai mangaka that has written yuri and her artwork was really good to look at, and Nangoku Banana; I believe she writes both BL and GL so there you have it. There's more, but forgot their names so I'll check them out later :)
Here's an interesting question. What made you guys stopped reading straight romance manga and moved to yaoi or yuri or both? Speaking from a psychological point of view, I would like to hear your opinions as to why read yaoi or yuri or both? Anybody studying psychology or such can use this type of info to help you out why most people read such type of manga.