While I grew up with 4kids, I prefer the RAI dub.
The 4kids VAs are okay (slightly better than SOME RAI ones), but I feel they censored out or Americanised too much. And they did some dumb things like make Musa a princess, which is just no. But I do like the opening of the 4kids quite a bit xD
RAI may have some shaky VAs, but I like it more. I think it's closer to the original and they don't censore out silly things. But I enjoy this dub more too. I could live with out some of the name changes though, but I don't mind that too much.
Also, shouldn't this be in the Winx Club Discussion Category?