I second BMTRIX's opinion on the DVD+r format, because I go through a ton of these +R discs for video work daily, and it is by far the most compatible across DVD players than the -R format, especially if you are talking about older DVD players. I used to use the -R format before I switched over. If your DVD player can read a +RW disc than that's better 'cause then you can record over it about 1000 times depending on your purpose (speed is a bit slow on the write). Price wise it is a bit more expensive than the other 2, but it is coming down fast.
As far as quality goes for video backups there is very minimal difference between the +/- R discs. They used to be speed difference between the two, but not these days. These days the new DVD players handle +R/-R and +RW format with ease. Then again, it depends on what sort of software and hardware you are using to burn these home videos too 'cause some of them are not 100% reliable or compatible with DVD players. Price wise the blank discs are almost the same these days, except for the +RW discs. I get better deals for most part with +R discs. Overall, I like +R discs better 'cause they are cheap, fast and compatible across most players (if not all).