A DVD-5 is 4.7 GB, whereas a DVD-9 is 8.5 GB, so it can hold more information, thus the bitrate (and video quality) is higher. To burn a dual-layer copy, you need a burner that can do dual-layer, and you need dual-layer blank media (I'd recommend Verbatim DVD+R DL discs).

If you want Revisited, definitely go with the dual-layer DVD-9 - it has one or two "corrections" from the single-layer version, and the video quality is higher.

If you're simply looking for video quality, go with the modified 2004 SE, which is 1080p AVCHD - basically a Blu-Ray on a dual-layer DVD. However, this is NOT REVISTED - it's a modified version of the 2004 SE, with CG Jabba, Rontos, etc., but with Han shooting first instead of Greedo.

Note that for either of those, you DO need a dual-layer burner and media.