DVD-R is the most suitable media for burning when you want the absolute best
in cross compatibility with older systems or dvd-video players. For
example - if you're burning actual video files, or you're making a
slideshow disc to play on a normal DVD player. Older computers and a
lot of older DVD players will often only accept DVD-R discs.
DVD+R is the most suitable
media to burn if you are archiving files. These discs have more error
checking built in to the burn pattern and are therefore more tolerant
of minor imperfections in the burn and the disc structure, so should in
theory last even longer than DVD-R discs.
We use Taiyo Yuden (JVC) DVD Master Quality discs for burning all our
scans to discs for clients. They are very very reliable and habitually
come out on top of DVD media tests.