LOL what's up with the One Piece hating? Did you guys actually watch the original Japanese version, or at least FUNimation's uncut version? Because if you're going to judge One Piece on 4kids' dub (I think we all know how terrible they butchered the series) you're making a terrible mistake.
Ah well, I'm not going to defend my favorite anime of all time, One Piece, here, since this topic is about the WORST anime ever, which is a hard one, since I've never seen an anime that really made me ****** off because of it's low quality. Naruto Shippuuden comes pretty close though, but that's just because I actually really liked the original Naruto series, but it went terribly downhill halfway Shippuuden in my opinion. Crappy plot, unoriginal cliché characters with horrible unoriginal designs (I mean what's up with Pain being a Naruto-clone? They rest of Akatsuki is not very original either), villains (again talking about Akatsuki) without a strong moral (if they have a moral at all?), an emo whiny son-of-a-b**** as the main villain (if you can call Sasugay a villain in the first place), no, seriously, Shippuuden has destroyed Naruto for me.