While the voices are very good so far, it might be a bit too early to really compare them to other games. Dubbing wise, I think XII and XIII are probably still superior if only because of how high quality they are. But, I do think that the dubbing for this game is shaping up to be much better than other recent English FF games like Type-0 HD, which had a so so dub, in my opinion.
I'll definitely agree with you there. XII has the best localization of any mainline FF to date (good English VAs, reasonable lip syncing, wonderful adaption of the original script, beautiful nuance in re-creating the Ivalice aesthetic), while the technical and production values for XIII are unprecedented despite some occasional dodgy performances (lip synching to the English VAs, getting so many high-profile VAs in to voice the main characters, getting the translation pretty darn close to the original even if some of the nuance and finer lore details were lost or trimmed).
I also agree that the dub for Type-0 wasn't very good... Seriously had to cover my ears or switch to Japanese for some of the lines from Nine and other members of Class Zero (I think they must have been trying to imitate how they had handled the characters from The World Ends With You, and it didn't work with extensive voice acting). At least the translation was extremely close to the Japanese original, so you could switch to the JP track and know you hadn't lost any story details or subtleties. I also wish they could have put more effort into the English dub for Mobius. Seriously, some of the lines sound so flat, and the sound balance with FXs and music is just off.
For myself I also like the localization for X-2: while not as good as XII by any means, it learned from the mistakes of X and did its best on improving while the game essentially used the same technology over again.