The etching / stamping backups seem to be the most durable and cost effective as per Lopp's tests:

https://jlopp.github.io/metal-bitcoin-storage-reviews/

Conversely, backups with moving parts (like the casette models) are less durable and way more expensive... Easier to set up I suppose.

You could go cheaper still by buying stainless steel business cards and an engraving pen.