Let me state up front that this is not necessarily a 'Best of' list; I didn't have time to read everything and I'm sure that there's some good stuff that came out in 2007 that I just haven't gotten to yet.
That said, here are my picks for my favorite graphic novels and manga from 2007 (I'll follow later in the week with a post on favorite comic books):
Original Graphic Novels:
The Arrival by Shaun Tan
The Arrival actually came out in 2006 in Tan's native Australia, but it didn't really hit U.S. shores until this year so I feel justified in including it. Tan, generally a creator of picture books for children, has created a wordless graphic novel that seeks to give the immigrant experience to the reader. Our nameless immigrant travels across the ocean to a strange land; at first we think we're in a early 20th century on Earth milieu, but soon we discover that we're in a world that clashes with the bizarre and wouldn't be out of place in a Jim Woodring comic. The sights are odd, the flora and fauna are odd, the customs are odd, and we don't understand the language. I don't know if it's possible for a comic to be a truly immersive experience, but The Arrival comes about as close as possible.
Bookhunter by Jason Shiga
Set in the early 1970s, Shiga's Bookhunter takes the police procedural and sets in the world of a major city public library. For anyone who enjoys a good comic this is entertaining; for a library geek like myself, it's paper-and-ink crack. Bookhunter goes a long way in solidifying Shiga's reputation as an unheralded comics genius. (You can read Bookhunter online in its entirety here, though I strongly suggest that this is a comic best experienced in print.)
Zombies Calling by Faith Erin Hicks
You might expect that at this point there wouldn't be anything new in zombie comics. I would have thought such an opinion to be correct, had it not been for Faith Erin Hicks' debut graphic novel Zombies Calling. Three university students find to their surprise that their campus is being overrun by zombies, and they use their knowledge gleaned from watching zombie movies to survive. It has just the right mixture of humor, satire, action, drama and pathos; and Hicks's agreeable art (reminiscent of fellow Canadian Brian Lee O'Malley) is perfect for this kind of story.
Yotsuba&! by Kiyohiko Azuma
2007 saw the resumption of English publication of one of my all-time favorite manga series, Kiyohiko Azuma's delightful slice-of-life comedy Yotsuba&! No other comic being published today makes me laugh so much, and it's good clean fun at that. Charming, sweet and fun, it serves as a perfect example of how to make good comics.
Town of Evening Calm, Country of Cherry Blossoms by Fumiyo Kouno
A collection of two (or three, depending on how you count them) stories dealing with the long-term effects of the atomic bomb on the people of Hiroshima, Kouno's Town of Evening Calm, Country of Cherry Blossoms pulls off the tough task of being an 'important' work without seeming like it's trying to hard. Despite the sometimes depressing themes, this is not a depressing book. We see the bomb as a ghost hanging over the people, but it is a ghost that they learn to deal with. Heartbreaking, yet strangely uplifting in the way the characters not just survive but also live. It has stayed with me ever since reading it.