It depends on what you are looking for. Tails and Liberte have the primary goal of not leaving any forensically recoverable traces after you shut down. In some ways this can be even better than FDE, primarily there is nothing encrypted for you to be forced to turn over encryption keys for. On the other hand, if you use persistence then you are back at using FDE. Tails has a MAC spoofer for breaking linkability between WiFi access points and sessions. Additionally, Tails also doesn't keep entry guards for Tor which removes a fingerprint of entry guards if you use WiFi from multiple different access points (or even the same access point over sessions). On the down side, not having entry guards means that you will be much more quickly traced in the first place. I see Tails as being largely a mobile OS, for somebody who uses WiFi from many different access points. Whonix is more focused on preventing you from being traced by hackers than it is on making sure that it doesn't leave behind any forensic traces of what you did. It does this by isolating the browser away from Tor, and also such that it is unaware of its external IP address. You can still use FDE to prevent forensics teams from recovering logs and such, however you could be held in contempt of court if you refuse to turn over your passphrase, depending largely on where you live and how badly they want you. There is also always the risk that you could be subjected to a cold boot attack or similar. I personally lean more towards Qubes than anything, it has functionality really similar to Whonix but it takes it several steps further such that everything is isolated into its own user defined security domain. This means you can protect your private encryption keys, your external IP address, Tor, etc. It also has advanced features such as hardware isolation, and a variety of different security tools based on its isolation techniques.