Generally DVD+R because in the early days they would burn faster on some burners, especially my first one, a 2.4X Sony. I did read all the + and -R forums some years ago, but have forgotten most of what I knew about the differences.
Point is, I've never understoood if there is a specific advantage to one or the other depending on the application.
Just remembered: I began by using only -R because they were compatible with most DVD players (especially in Europe). But then I discovered that with a firmware update on my Sony 2.4 I could burn at 4X with +R discs. As more and more people got newer DVD players, the issue of compatibility became moot. I just saw a little comparison on HP's site that is interesing, more or less the points I'd forgotten
http://www.hp.ca/portal/hho/dee/musi...vd_compare.php
Look at the features chart at the bottom.