I mean, I read as much as I can of incandescens' work as I can for the play on language and the interesting twist to characters that makes me see more about what they're about and only gogoangelgunboy can put as much as incandescens can into 100 words (check out her recent drabble run); but she does it On Demand and nearly all the time. I read lots of zangetsugirl's stuff for insight into zanpakutou. I also love Darth Ammonite's takes on Nanao and Shunsui with just judicious touches of Ukitake.
When I need my angst, romance, and smut fixes, I often go with anything by stark_black, and for bdsm of all levels 2metaldog just really does it for me as she's really good about warning about non-con and does some really beautiful and hot scene building. She also does a lot of interesting pairings and builds some really, really strong, loving relationships that I love.
For a mix of great stories with lots of good slash, I'm finding that Sleeps with Coyotes really teaches me a lot about long story structure, too. And, wow, is she prolific, there's always something new and interesting.
I read lots of other stuff and like a lot of it and fav like happy (waves at flist); but... these are my staples. I just read a beautifully framed and structured Byakuya/Ulquiorra by etchedindigital. She's got great stuff, too. I need to catch up a bit more. *laughs*