The longevity of DVD-R optical media is how and where you store them. Keep them in a temperature control environment or away from chemicals that deteriorating the data layer is always a good practice. If you don’t have the luxury with environmental control, get the expensive flash media or highly-resistant optical media like the Mitsubishi‘s ARLEDIA.
The ARLEDIA got its name from the Gold-Silver (AU-AG) reflective film layer. The highly-resistant gold-Silver complex will prevent chemical oxidation and improve reflectivity, result with a better compatibility and durability optical media. Mitsubishi says the $5.50 ARLEDIA 4.7GB DVD-R has twice the life expectancy compare to a typical DVD-R in lab a testing environment of 88 degree Celsius / 80% RH.