I don’t think there’s any particular disagreement here, it’s just that there’s no “best” format. Everything is a tradeoff, it just depends what your goals are.
If we’re talking about what’s most likely to survive a hypothetical society-destroying disaster, then simpler is better. Records (e.g. vinyl) easily wins here, since playback requires only a mechanical device. You don’t even need an understanding of electromagnetism to design one. Analog tape is a safe next best option, since playback still relies on relatively simple physical principals.
Anything digital is at a disadvantage in this scenario simply because playback requires some knowledge of the format of the data. A PCM audio format encoded directly in a simple linear physical form (no error correction, no checksums, etc.) will be pretty easy for anyone capable of building a playback device to figure out. But something like an MP3 on a USB drive involves so many layers of protocols and formats that it’s going to be really difficult for anyone without that knowledge to interpret.
If we’re not assuming some mass loss of technical knowledge, digital becomes a lot more attractive. However, there are still tradeoffs.
A single copy on a CD is easy to store and play back, but it’s a terrible archival format. As you point out, CDs are easily damaged and they were never designed to be all that resilient. 3 copies of the same thing on 3 CDs, one at your house, one at a friend’s house, and one in the seed vault at Svalbard is a totally different scenario, especially if you check the CDs every 3 months and replace any one that’s beginning to degrade. You do have to actively maintain your archive now, though, which is another tradeoff.
We can still do much better. Archival tape formats support levels of redundancy that allow data to be fully recovered even if significant portions of a tape have been lost entirely due to damage. And again, we can keep multiple copies, in multiple locations. It’s worth repeating that any long term archive requires intentional management. However, if you neglect that, you’re still going to be much better off with a highly redundant digital tape format than something like a CD, which was simply never intended for this purpose.
This is where online services come into play. As an individual, you don’t have physical access to anything akin to the Global Seed Bank. But you do have access to services like Amazon Glacier, which are designed for redundant archival storage, with options to have your data housed in multiple locations distributed around the globe. The chances of Amazon unintentionally losing your data are as close to zero as a consumer could reasonably care about, and they’ll do most of the management for you.
However, any form of online storage comes with the downside that any entity with access to your account can, with a single action, cause all of your data to be deleted. This is why local, offline storage still matters. Keep a copy on a drive at home that you check once a year, plus a copy at a friend’s house if you really want to be safe, and now you have a backup scheme which admittedly requires a society with deep technical knowledge to maintain, but which will easily outlast anything you can manage with analog storage. If that’s your aim at all.
