I actually really, really, really enjoy Black Butler, especially the Book of Circus (both anime and manga). I love the graphics, I love the characters, and I LOVE the whole atmosphere of this manga. It's amazing. One thing I will admit is that the plot is complete shit, but for me that doesn't take away from the actual anime/manga because I don't watch Black Butler for that. It's just really different from some of the things I watch, and I love the Ciel/Sebastian dynamic (and how even if the author wants it to/fans want it to, there is no direct romance in this manga, woot).
Favourite characters are Ciel, Sebastian and Grell. Quite amusing. It's funny yet eerie, and has interesting twists and turns, combined with a lot of dark humor and the old Victorian feeling. I also like the development of Ciel and Sebastian as characters. I think that's what I look forward to the most.
Too bad Black Butler isn't great with updating chapters. Ugghghhhghglhglohsarshgdsurd