Yeah Dragonball Z's Cantonese dub was very good. I saw a few episodes of the cantonese dub on tv while I was in Hong Kong, it's not bad but all dub sounds unnatural to me if I watched the original japanese before. A problem with cantonese dub is that there are probably only a handful of Voice actors so you can recgonise the same voice for another character in another series.
haha, i think watching the original and reading the subs is better, cause the dubs can sometimes come out sounding weird.. so i agree with pensuked.. =p