i like the first format because i can use it on core version, i like to use the original client and not third party client, what make your bitcoin really secure is the user behind the security of his coin not the way you do it, i like to secure with trezor or usd stick, which are portable and can be used everywhere, trezor for possible infected public pc is very good, usb on my home work great
are you saying you can use your wallet.dat in trezor? or any hardware wallets?