Safe Offline OS?

[BlockchainHelp?]

Hey Everyone,

At the moment I have 2 USB's with my 4 private keys backed up on each, I used Tails to create the private keys with Bitcoin-QT, I have since removed Tails since I don't use Tor etc and needed the USB and now I want to print my private keys to have a hard copy but i dnt wanna compromise my keys by using my windows machine

Which OS is best to put onto a USB to boot into to access my private keys from my 2 usb's?