For me, it's DVD-Rs because my DVD player reads DVD-Rs and I prefer to watch them on a large screen.
The bottomline line is if you are planning to play it on DVD players, check which formats it reads. If you're playing it on your PC-DVD Writer, either one will do. In addition, do note that not all DVD+R/-R medias are made equal ... there are more reliable brands such as Fujifilm (which I'm currently using).
All the best!