None.

For individual users, the best solution for storing a large amount of bitcoin is multisig-timelock addresses.

Like BitKey's Solution: https://medium.com/bitkey-blog/bitkey-s-multisig-timelock-address-22ff41c1b017

This has a big advantage over hardware wallets. Users no longer need to worry about coin thieves and key/seed-paper loss disasters.

The hardware wallet can't solve the problem of seed paper backup, and it can never solve the supply chain attack problem.