Also, there hasn't really been a filler arc in One Piece in a long time due to how fast the manga is paced.
I want to say though that, with the exception of G8, I DON'T think One Piece fillers are better than Bleach fillers. At least, not the full arcs. The Bount arc and especially the Zanpaktou Rebellion arcs are almost as good as the non-filler material.
The Amagai arc is kind of spoiled by the annoying little girl, but even that arc wasn't bad.
It's just that, like, when a filler arc actually takes the time to establish real characters, and enemies that, if you didn't know it was filler, you'd actually believe were a threat, and give the arc enough time to develop the way a real story arc would, they can actually come out pretty good.
I mean, shit, I'm still kind of interested to see that last surviving Bount and the doctor that made them show up again in a future filler arc. Those two feel like real characters that are actually a part of the world.
You can even see this in Naruto. While the 3Tails and 6 Tails filler arcs aren't nearly as good as the canon episodes, they were far superior to the Filler Hell of the original series. Unfortunately, the current Naruto filler is pretty much Filler Hell all over again.