There isn't much gachi yuri anime, and most of it sucks. I'd consider Maria-sama ga Miteru and Strawberry Panic the classics. Yuru Yuri would be the most well known proper yuri anime, though it's a comedy more than anything else. If you're fine with Kirara type stuff (cute girls doing cute things with varying degrees of subtext), there are a lot of good animes, such as Hidamari Sketch or Yuru Camp.