I can see how One Piece is very popular due to its drawing style and assortment of interesting characters. But for me it is rather boring. The story is too drawn out and convoluted. I mean the thing is already over 10,000 pages long and the creator only said a year or two ago that he felt he was halfway through the series.

Because anime is junk ruined by filler arcs?

But Nurarihyon no Mago charting at 9 is suprising. I thought it's niche series.

I really like the manga but they fucked really bad the anime.

VGChartz tracking manga sales confirmedz?

Actually it is halfway  right now...While Naruto's (wich is already pretty big) part 2 is ending,  One piece's part 2 is noly starting.

Erza would love a word with you.

I am loving Fairytail right. It's all about magic, magic and magic! It also has a flying cat too!

As for OP I am not surprised and it's no wonder it's the no. 1 manga in Japan. It has great story, great action, funny, unique and lovable characters. OP also has a JRPG elements on it. Going on a journey. Meeting up new members along the way. It also a ship, a flying ship!! (well not entirely).  Sogeking!!! Gear Secondo!! Jet-o Pistol!!!!

This makes one piece popular!

Nope. no joke. I read a lot of manga and I find the best stories are those that are concise. When manga artists go and on they become victim to one of two things. One they lose the originality that made their work unique, that or their work becomes repetitive. In the case of One Piece I think it is the second. This and the lack of focus on overall plot are what bother me most. However, since it is a shonen manga most of the adolescent readership don't seem to care.

Not that I'm trying to bash Eiichiro Oda. He has accomplished something incredible considering it is his first full length work and he had no previous following.  And he publishes in Shonen Weekly so thats an output of about 20 pages a week. That certainly will cause an author to sacrifice quality of story to create the required volume in such a short time frame. At any rate there is no denying how huge One Piece now is. 

I don't find One Piece particular interesting too...my favourite Manga of all time are FMA, Death Note and now Bakuman, which is really a piece of art! Did they already end the series in Japan? I though the manga was extremely successful there!