Always use minus - over plus + because the plus DVD's seem to not work on older home dvd players. When I burnt movies for other people and they complained that the movie didn't work it took me a long time to figure out what was happening. They would tell me it would play fine on their computer but not in their home DVD player.
I think the quality is the same.This is a DVD player compatibility isue.I usually use DVD-R but some times i must use DVD+R because my external DVD recorder doesn't burn on DVD-Rs.