Q: What type of flash media has the best long-term storage reliability?
I'm aware that all flash media has varied limits on lifetime write cycles, and that there are better media for long term storage, such as archive-quality optical, tape, and long term cloud storage. But I'm specifically looking for something that could be kept on my person or in a desk drawer or even a fireproof safe, for instance, and which can store small amounts of data, which can be added to very occasionally over time, and is portable and easy to access in an emergency.
Use Case / Background:
This is for emergency/critical personal info that is sensitive, but needs to be accessed quickly -- ranging from financial access info to security keys for cloud storage, for instance. I've just had far too many USB drives and SD cards suddenly become corrupt because they sat in a drawer for a year or two and presumably just wore out from age; this is precisely what I'd like to avoid (or minimize the chance of, at least).
I'm not looking for brand/product recommendations (that would be out of scope for SU) but for specific types or technologies that are known to be more reliable and stable (of course, if one brand has a unique technology that works well for this case, that would be relevant). I can use your answers to do my own product research. ;)