I use DVDShrink. It burns automatically after encoding, but I was told that it's just actually incorporating Nero's DVD burning capabilities. I'm using the Nero that came with one of my drives.
Anyways, the media I've used are
Memorex 8x + and -
Fuji 8x -
GQ 4x and 8x +
Dynex 8x +
TDK 8x +
Verbatim Digital Movie 4x -
Any of those brands burned in the IOMagic/Benq will not work. They all bring up the "Check Region" error message on the Aiwa. Any of those brands burned on my Emprex/BTC 8x or my IOMagic/BTC 8X or my brother's HiVal (supposedly Optorite) 4x work fine, with the HiVal doing the most reliable burns (least amount of errors if any among the four drives).