As with my anime list, I decided to list the titles in this post alphabetically (well, alphabetically within each category) rather than worry about ranking them.
A Happily-Ever-After ending to a very sweet, very gay series. (The Amber Teahouse is simply awash with women of the yuri persuasion.) May we continue to see Sarasa and Seriho cameo in many more Fujieda series.
Even though this isn't manga-relevant, I'd like to mention again that I really appreciate Fujieda for writing a new story for every single drama CD based on his works. Excluding the Marimite drama CDs, my face falls a little every time I find that a drama CD I've gotten re-enacts an already existing story.
This story incorporates some of the less positive tropes of yuri but, in a way, transcends them. Blue Friend's themes about overcoming the past and the fear of opening up about the bad experiences in one's life to someone whose opinion one deeply cares about were poignant and well-integrated with the yuri between its two leads.
This story is a love letter to many of the fun tropes of yuri, made for a shoujo audience with nods to the older folks who know what series Nobara owes its heritage to. Even though I know that "yuri" isn't synonymous with "lesbian," etc, etc, I love that something like this (or Blue Friend, Sailor Moon, Cardcaptor Sakura, etc) can come out in Japan without the homophobes collectively getting their panties in a twist over "protecting" children from being exposed to the idea of same-sex relationships.
We loved it, we hated it, we loved to hate it. But really, we mostly loved it. I would have loved to see Yukino come out to her family (she seemed like she was just about to before this series ended), but the ending to this series was still great, and we know that Yukino and Setsuko will be happy. As not only a yuri series, but a series about growing up and sorting out one's life as a young adult, Octave was excellent.
Morishima Akiko knows how to hit all of the right buttons. She loves writing about cute, lovey-dovey adult couples, and I love her for it. Arisu was a hoot to follow, and I'm glad she got a Happily-Ever-After with the girl she wanted. (Among the other cute couples this series has covered.) I also love Renai Joshika for making same-sex marriage a prominent point of discussion.
My most "subjective" inclusion in this post. This was a highlight for me because it's the first time I've bought a tankoubon by someone whose doujinshi I have liked for years. For a very particular niche of the yuri fandom, this book's publication was a huge "OMG!" moment.
Top 5 Series That Have Been Collected Into Tankoubon This Past Year But Are Still Ongoing:
For Fumi coming out as a lesbian to her straight friends- showing how much she has grown since she first came out- and Orie and Hinako getting married and coming out to Orie's family. I still love this series to pieces.
For being an sweet look at domestic bliss, starring Suu and her wife Kina. (Plus Komugi and Hayase, the lesbian couple next door, and Kina's sister Kana, the lesbian Don Juan who finally meets her match.) Watching Kina and Suu just makes me happy, the other characters are fun, and I love Minamoto Hisanari for making a case for two women to be able to use the term "wife" for each other.
Speaking of transcending negative tropes...but in this case, tropes that are ascribed to queer women across different media rather than simply yuri. Gunjo is a challenging read (in more than one sense), and that's refreshing when- as in this case- it's done well. I cried for the character who died in volume 2, and I'm on pins and needles waiting to see how things end for Gunjo's nameless lesbian protagonist and the woman she threw everything away for.
Out of all of the titles I've read for the first time this year, Omoi no Kakera easily has my favorite protagonist. Mika is a loveable, intelligent, refreshingly self-aware lesbian, and I'm looking forward to seeing more of her life.
Sasameki Koto occupies a gray space between this category and the first category because it has ended but its final tankoubon hasn't been published yet. For its loveable characters and depiction of what it's like to be a gay teen in a way that rings true again and again, Sasameki Koto always deserves a spot on this list. I'm really looking forward to getting that final volume.
Series That Haven't Been Published As Tankoubon Yet:
Collectors is about Shinobu and Takako, two women who are complete nerds for very different things. Shinobu loves books and Takako loves fashion. They love each other despite, and to some extent because of their different passions. (Someone who isn't passionate about anything wouldn't make someone who is happy, imho.) I love the premise and look forward to seeing it in tankoubon form.
The return of Morinaga Milk's first (and arguably most) popular couple! And it addresses an issue that Girl Friends, realistic though it was, tiptoed around- coming out! (Four for you, Morinaga Milk! You go, Morinaga Milk!) The announcement of Nana and Hitomi's return was the best yuri news of 2011.
Must-Read Manga of Yuri Interest Published in English:
For continuing to re-introduce Tomoyo, one of yuri's most iconic classic characters.