Let's hit this point by point, according to Kula's specifications.
Talented voice actors
Regardless of what other people on this forum think of English voice actors, I think you have a first-string team of voice actors in each region (Houston, Dallas, L.A., New York, Vancouver), and it basically depends on what group of actors would be used.
High quality acting
Keep in mind you have to realize that when all is said and done, DB/Z/GT is still a kids' show. On one hand I don't expect the acting to be on a par with other quality shows like Bebop or FMA, but on the other hand, I don't want a 4Kids exaggerated dub either.
Voices that are carefully cast for each character, that are appropriate when compared to the original Japanese VAs
Here's something that might be shocking to people that may not know much about the whole English casting process: the particular dubbing group/company may make initial choices for characters, but the ultimate decision as to who plays which character lies with the Japanese. The Japanese can make casting decisions that seem illogical, but because the Japanese made the final choice, that's what the American cast has to go with.
Scott McNeil (for example) might be the preferred voice that Company A might want for (say) Vegeta, but if the Japanese say it needs to be Brad Swaile, then no amount of prodding and persuading by Company A and its supporters will change the Japanese's decision to go with Brad instead of Scott.
One VA per character or at least cast VAs that can do distinctive voices for more than one character
Again, the American company may make suggestions, but the Japanese have the final say. If the Japanese make casting decisions that indicate that one particular actor be the voice of two or three particular roles, then that's what the American company has to go with.
Accurate script
No pointless adlibs
This may be all well and good, but if the English script is as closely accurate to the letter to the possible, you run the risk of the script being extremely dry and uninteresting. The acting may be done very well, but if the script is dull and dry, then you could very well be left a show with all its life taken out of it.
You also have to remember that the script needs to match the mouth flaps, because English dubs tend to make the words fit the mouth flaps. English speakers tend to want what their watching match the mouth movements, as opposed to the Japanese who tend to not care one way or another how the words fit the mouth flaps. The lines will need to be accurate and convey the point across, but if it doesn't fit the flaps, it will look very shoddy and "typical bad dubbing found in dubbed live-action martial arts films from the 1970s".
No unnecessary noises coming from characters when there should be silence
It is possible to do foley (those grunts and other noises in between the spoken lines) for characters without overdoing it - believe it or not, Japanese foley/reaction noises tend to be overexaggerated than how it would be done in English.
Original JP music
As long as the American company is able to use the original Japanese BGM for the English dub, it's fine.
As far as if I would watch it over the long-term, I'm of the same mindset of Julian, Mike, and Meri. I'd watch it for a little bit, make my judgments, and then maybe check out what other episodes I'd like to check out in English.
And I can admit voices haven't differed much at all between characters in a few dubs,but I think part of this is the fact that the characters are speaking English.Which is most of our natural languages,thus making it easier for you to recognize them at times... 
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She does better as Gohan, but Kyle Hebert does well with him (grown-up) as well.
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