This is a really subjective topic but personally? Yeah. Of all the comics I read (and I mean all; western, Japanese, whatever) it's my favorite.
I could go on about how much I love Oda's art, his pacing, his characterization, but the thing I adore most about OP isn't any of that. It's that I trust Oda. I think he knows what he's doing. I've never once gotten the feeling that something was half-assed, or that he's making it up as he goes along.
Crazy as the world of One Piece is, it's also fully realized. It's well-defined, it has rules, it functions. It's complete. I get the sense of a world that WORKS outside of Luffy and Co.'s adventures. Many times in stories, it feels as if the world was created just as a background for the heroes–a town doesn't exist until they get there, and ceases to exist after they leave. With One Piece I never get that feeling. Everyone that Luffy and Co. meet has a history, their own concerns, their own goals and motivations. I don't get the impression that the world exists to serve the story. (Does that make sense?)
I love that he drops hints for plots to come dozens, sometimes hundreds of chapters in advance. Dragon, Blackbeard, The Will of D, the Poneglyphs, the "Lost History", the Ancient Weapons--all of it has come to play in the story in a major way, from plots which initially seemed frivolous to Luffy's ultimate goal of the One Piece. I remember thinking in the middle of the Skypeia arc, "This is pointless, how is this getting them closer to Raftel?" But then when the payoff came, it proved the entire arc worth it.
Basically, I trust that Oda is a master of his characters and his world, and that he knows, ultimately, where the whole thing is going. I've never read One Piece and thought, "Luffy would never do that" or "That doesn't make sense" or even "I could have written that better." Whatever choices that Oda makes with the plot, I trust that it works, or that it will make sense to me later.
Best of all, I get the sense that Oda still LOVES it. I feel like even though it's been ten years, he still genuinely cares about these people and this mad little universe he's created, he cares about telling their story. And I guess that's the heart of it; I love that Oda loves it, that he seems to care about it as much as we crazy fans do, and that he wants to do it justice.
So often I've seen creators peak and then decide to stop caring and start coasting, delivering sub-par work because they know people will read/watch/buy it anyway. But Oda hasn't done that; he's as enthusiastic now as he was in the beginning.
(I could be totally wrong, of course--Oda might be completely sick of the story. I know I would be after TEN GODDAMNED YEARS. But if he is, it doesn't show.)
Argh, there are too many things that I love about One Piece to list. It's all opinion anyway, which means this whole post can pretty much be summarized as ONE PIECE LIEK TOTALLY RULZ, YO, I <3 ODA LOLLERSKATES!!11one!