His opinion on tape is pretty well accepted. It's not really intended for long-term archiving; it's intended for portability and ease of reuse.

Unfortunately, DVD-R (not RW) is probably your best choice. (I've not looked into the aspect of the archive suitability of the various DVD-R dyes. One of the CD-R dyes was chemically unstable and would degrade over time. Make sure the same is not true of the DVD-R ones.) I've had to deal with this in the past and it's not fun. Then again, no aspect of backup and archiving is fun.

Anyway, since DVD-Rs are irretrievably physically changed when burned, they stack up better than magnetic media, which could be affected by passing magnetic fields and which loses its magnetic polarities over time, or RW media, which will lose its data over the passage of time as the thin layer of metal loses its crystallization.