It depends mostly on preference and your hardware. Some older standalone players were not compatible with +r. That is less of an issue on newer hardware. I think that you will find the majority use dvd-r for video recording. Probably the most important thing is to use high quality media such as Verbatim or Taiyo Yuden.
Amen to that. Quality blank media is such an important role in making good quality back-ups. And yet so many people easily overlook it, thinking a blank disc is a blank disc. And it's just not true.
The answer to your question, "which is better for recording dvd- or dvd+" is...depends. If your recorder/player does not recognize +rs, then -rs are best. If your recorder/player doesn't reconize -rs, then +rs will be the best. Simple, isn't it?
Just don't forget the excellent advice 7thsinger gave about booktyping to DVD-ROM, that way you never have to worry if the player you want to watch your movie on is compatible with your media.(i.e- friends house or anywhere else).
