Eh,
the worst dub to me would have to be the Naruto dub, really now I'm still trying to figure out how they got "Believe it!!!!!!!!!" outta "Dattebayo!" The voices are the worst problem with the dubs. They sound terrible, my opinion on the voices:
Naruto: no..........just say no......
Sakura: You know that annoying girl that wont leave you alone , that's her.
Sasuke: He sounds like he's 25 years old, plus he sound more emo than the sub.
Orochimaru: He sounds like a drunken british guy.
Shino: He sounds like a 50 year old man having a heart attack.
Hinata: Her voice is just to squeaky compared to the sub.
Kiba: Yahoooooooooooooooooohhh, right he doesnt sound boyish enough.
Konohamaru: He sounds like a less squeaky version of Donald Duck.
Ino: Look at Sakura description.
Shikamaru: If they made his voice a little less deeper it would have been okay I guess, but I hate how they pronounce his name Shittahmaru.
Chouji: His voice is way to deep.
Jiyaira: His voice doesnt sound perverted enough, his laugh just isnt the same.
Iruka: To cheerful of a voice.
Kakashi: His voice would have sounded better if it wasnt so stressful at times.
Maito Gai: His voice sounds to stressful and not enough freedom.
Anko: Sounds to young even for her.
Asuma: His voice is just to plain.
Kurenai: Her voice sounds like she always worries about something.
Rock Lee: His voice was okay, it need more spirit though.
Tenten: Sounds to girly girl like.
Neji: Sounds way to old for his age, like a 40 year old, and it's just to deep.
Gaara: I hate this voice, they failed at making him sound creepy.
Kankorou: Take 5 years off his voice and it would be okay.
Temari: Sounds way to girly girl prep like.
The 3rd Hokage: Eh, needs more emotion.
Kabuto: Sounds like a slightly drunken british person.
Kin: Sounded to deep.
Zaku: Sounded to low.
Dosu: Just needed help.
Hayate: If they'd make him sound more sickish then it would have sounded better.
Well, if I missed anyone then to bad, I think you get my point.