The Region 1 DVD of the film has been out for a while now, and differs very little from the Region 4 release. It also does not have anything in the way of extras apart from the theatrical trailer, so if the additional trailers on the Region 4 release could tip the balance in favour of the Region 4. The few available reviews of the DVD seem to offer distinctly different views on the quality of the video, which makes things just a wee bit difficult for comparative purposes. It seems unlikely however that the Region 1 release offers anything significantly better in quality than the Region 4 release.
The Region 5 release of the film (under its alternate title of 1947 Earth) offers another option if you care to wander to another region. Unfortunately it is not 16x9 enhanced but does offer the soundtrack in Dolby Digital 5.1 and by the sounds of it slightly more comprehensive subtitles, as they apparently include the song lyrics too. There are no extras on the disc. The sole review I located mentions some poor encoding resulting in double images in pan shots.
I have not been able to track down any releases from other regions, which of course does not mean that they don't exist, so it would seem that on the balance the Region 4 is probably the better option of those available.