This year was fairly awful for individual characters. Most of the top shows were good either because of their setting or because of their entire cast playing off each other.
Considering the show itself was not so well received, it's hard to shower any particular accolades onto it, but I thought the female lead from Dance in the Vampire Bund was the my favorite individual character. She was multi-faceted, weak at times, powerful at times, is shown with different bits of character development at different stages of her life. Best of all, she manages to desire the male lead without hopelessly depending on him in the anime-style diminutive way. This was particularly fun to watch considering sexuality was such a rich theme in that series, and you can tell that the voice actress very much enjoyed the role. For me, the character turned Dance in the Vampire Bund from a mediocre thriller to one of those movies that ends up at an awards ceremony solely for its lead, absent in every other category of storytelling.
Runner-up would be Yaichi (white hair) from Saraiya Goyou, who is only held up by the fact that he's in an ensemble cast and only gets to truly shine in the last few episodes of the series. Again, we have the chance to see a character throughout their lives and this time, the differences are astonishing. As we learn more about him, Yaichi's character goes through this quiet metamorphosis in our minds, made all the more disturbing by the fact that the character has not actually changed at all -- he is simply revealing what was always there, draping the backgrounds of every scene. The character cements why Saraiya Goyou is an example of sublime characterization in a more mature drama; there are no wasted moments and the mood is subtle, but with dialogue pointed and subtextual enough to develop the characters without ever resorting to melodrama.
As for overall cast, it would be Durarara!! for me. The characters were quirky without being one-note or obnoxious. Most importantly, by the end of the 24 episodes, we see that many of these humourous moments are just facades. But nobody ever calls this out, either because they are ignorant, or because they wish to keep up their own facade to maintain a panorama of normality. The general consensus is that the second half of Durarara!! failed to live up to the build up of the first. I see that as proof of the cast's quality and the strength of character interaction in this series, as it was only when the characters decided to hole up in isolation, becoming their own leads in what's supposed to be a gallery of supporting roles, that the show fell apart.