I recommend paper in 2 copies that will never be seen between them.
What do you think would be a great hardware wallet to date?
Discussion
What happens to the paper in case of a fire? I don't use any hardware wallets or 3rd party software. I have a couple of heat resistant metal cards with BIP38 keys engraved on them and I have three encrypted pendrives that duplicate each other.
How much coincidence should happen so that the fire reaches the two copies at the same time in different places that have never been seen before?
The metal card seems like a good way to store, which one do you recommend?
I'm sorry. It was late and I misunderstood you. I somehow thought 1 key split on 2 pieces of paper.
As for metal cards. I use ISO-4955 (or similar) metal plates which have been hardened and are corrosion resistant. Titanium plates are also an option but more expensive.