all linux distro can be secure, my favourite method is:
- download debian netinstall
- install it on a usb key (even 8GB is more than enough)
- of course i choose full disk encryption during install
- boot from usb (can boot on any computer)
- install a few packages (a gui, electrum wallet, whatever you like but only what is essential)
- if you are a linux pro you can configure further security (tons of tutorials online) otherwise go to next step
- done, enjoy your bitcoins
now all your system is on an encrypted usb key (do not forget the passphrase!), you can boot anywhere on almost any existing compoter, all files get saved on the usb and you have no access to the host computer (and viceversa)
do not use kali, it's a distribution meant to test security, not to be secure
you can use tails but is overkill, it is meant to (try to) be anonymous, works on tor network and you have to use a modified version of firefox, depending on your needs can be a good choice (btw i wouldn't use it only for btc)
i wouldn't use the other bitcoin oriented distros as well (i wouldn't trust), i know for sure that debian has excellent and safe code and so i would build my system on top of that
Also, the derp mentioning kali linux forgot to mention that all commands are run as root on that particular distro unless you specifically set up a user account, definitely what you
don't want to do when using Bitcoin.
With a little patience and reading it won't take long until you can build a nice gentoo from scratch and only emerge the packages you need.
