Hrrmmm... Really not enjoying the Japanese DBZ Cast hate in this thread, considering Masako Nozawa is regarded in Japan as Son Goku over any and, considering, I grew up with that Goku, for me as well. Same with the rest of the cast.
I don't know, honestly everyone is allowed ot enjoy one voice over another, and I do agree that Nozawa as Goku is very odd to the ears for American viewers and could even be considered lazy casting on the Japanese side, but she really makes the character her own more than any other voice for him, I feel. Sean never really played him innocently enough, I feel, though that was more the script and direction than anything else. Same with Mayumi Tanaka as Kuririn; much more appropriate for that character both in size, personality, and overall attitude...
But I can agree there are some bad Japanese dubs out there. Maka Albarn from Soul Eater was terrible at first, completely lacking in tone and emotion. Furthermore, Yu Yu Hakusho had plenty of dull performances, with only a few saving graces from Mayumi Tanaka and Shigure Chiba.
But as for adaptations of American shows, Beast Wars was utterly trashed for some reason, and Disney movies have a rare big-miss, I've seen.
As for English Dubs which are considered better than the original products? Well, I can definitely see Cowboy Bebop, Big O, Baccano, and Yu Yu Hakusho ranking higher. The first three are helped a lot by the fact that the tone of them all is incredibly Western and the last because the original dub, as I said, was not very inspired.