There are some technical differences which are not interesting to most people these days.
The interesting differences between DVD+RW and DVD-RW are:
Some DVD and HDD/DVD recorders only support one of these formats, and if you have such a recorder, you are forced to use the supported format only.
The fastest DVD+RW is 8x and the fastest DVD-RW is 6x
Some recorders will allow you to do more advanced editing on a DVD-RW formatted in “DVD-VR” mode
Some recorders will flag true 16:9 widescreen content on DVD-RW media but not on DVD+RW media, thus making it unnecessary to manually select 16:9 or 4:3 when playing back the recording
DVD+RW discs are automatically finalized so that they can be played in other (non-recorder) DVD players, while DVD-RW have to be manually finalized or they will not be playable in other DVD players
You can have a look in the manual for your Panasonic HDD/DVD recorder, and it might list some features that are only supported for DVD+RW or DVD-RW or DVD-RW in DVD-VR mode
There’s no absolute answer as to which is better - it depends on your equipment and on your needs. I use both kinds.