Christ this isn't gonna sound biased or anything. rolls eyes
Oda.
Wait.
Don't be a dick and scroll down away from this obvious incindiary/controversial decision on my part.
I've read probably a roomfull of manga. Which to some may seem like a lot, but in the world of manga, it's beyond pitiful. And the majority of that is shonen which ultimately is saying, hypothetically, if the very first paragraph of War and Peace were the dumbest, most poorly constructed piece of grammatical garbage ever conceived and the contents of said massive volume represented manga as a whole, I would have read the first letter of the first word.
This means me declaring who is the greatest mangaka ever is akin to Johnny Knoxville choosing Stephen Hawkings' greatest idea.
This we know.
However, in what I have read of comics, and I have read some seminal pieces that the industry basically judges standards by, Oda' dedication not only to his work, but to his fans, is astounding. I think two years ago I would have said differently. I would probably have said Toriyama. In fact, if this is indeed the same thread, if you go back far enough then I think you'll even find me saying that. However, what I saw happen during 2007 was nothing short of a miracle. The amount of work required for the 10th Anniversary events and merchandise was staggering. If you run down the list you simply can't imagine that while supervising all of that shit, he wrote a frigging movie while keeping up with his already tiresome job as a regular author.
Now let's not get carried away this isn't a, "Toriyama drew every frame of animation himself! He' amazing!!!!111", it's not like Oda planned each and every aspect of it, but let's remember what country he's in. For every time someone decides to do something with the property, there has to be a meeting. There has to be a business trip. An exchanging of cards, boring-ass talks, and confirmations for little shit details like, "We'd like to use Glossy Black instead of Crow Black for Luffy's hair in this promo, is that ok?"
On top of that he did artwork and interviews for all the anniversay merchandise while keeping up with his story, fanmail/art AND somehow managed to sleep?
And what did we get? A reused JUMP cover for one volume?
The man is a machine and he said it best in that 3-part interview BF found around Christmas time. He does what he does because he knows what HE would like to read and he doesn't want to dissappoint fans the way a certain someone let him down when he was a kid.
On top of the dedication and drive you have his attention to detail, humor, ability to convey emotion like no other, blah blah, any of those things can be found in spades among the most talent authors, of which there are many. But Oda is the first and only managaka I've ever seen that is a fan of manga writing as a fan, for fans and its enough to bring a grown man to tears seeing what lengths he goes to. The man loves his job, he doesn't bitch, he doesn't whine, he doesn't take breaks to FUCKING PLAY VIDEO GAMES, he keeps going when he's sick and he does it all so that he can recreate the same joy that he experienced as a kid. This isn't me making up fantasy bullshit either, these are words from the man himself. That's love folks.
We can argue chicken and egg all day about whether or not OP would exist if not for other series, but Oda has raised the bar so high, that I doubt any other mangaka can even see it with binoculars.
He may only produce one long-running serial comic, but I'll de damned if it isn't shaping up to be one of the greatest stories ever told in manga. He's an amazing dude.
Here you'll find the results of a recently conducted survey by Oricon regarding everyone's favorite mangaka.
http://life.oricon.co.jp/news/080304.html
I was surprised by the overall results esp. #1 since all it suggests that shojo readers are Borg-like drones when it comes to a popular series since Yazawa didn't even place in top 4 of men's ranking and must have had a HELLUVA lot of female votes.