I like the Del Rey version, myself.
They generally do a really good job, but they've had a few big screw-ups, like having Chii call Fai King of Celes, but they don't change or censor anything (deliberately). Those screw-ups are pretty few and far in-between, though, so I'd recomend Del-Rey's translation. In comparison to Viz and Tokyopop, I think the Del Rey version is one of the best translations I've ever read.
Another good thing about Del Rey is that they have a whole list of notes on cultural references, crossovers and Japanese history that relates to the current book in the back of each volume, which is so helpful if you're not as savvy with some of the terms. They keep all the honorifics and nicknames in as well.
Bad points would only be the few big mistakes and the fact that they take all the taglines off the splash pages.
What kind of things do they have Fai say in Portuguese, then?
"Phi" is... kind of cute I guess. Do you pronounce it like "Fai" or like ..."Phee"?