1. LiveUSB/LiveCD Squad Edition Power Rankings:

A. LPS (Lightweight Portable Security) Public Edition (http://spi.dod.mil/lipose.htm)
http://distrowatch.com/table.php?distribution=lps
Size: 440MB (Deluxe Edition that comes with LibreOffice and other programs)
Created by: ATSPI Technology Office of AF
Purpose: fallback distro in case your military computer breaks and you have to access/edit/view top secret information
Official Flyer: http://spi.dod.mil/docs/LPS_DS.pdf
Pros: Created and maintained by the military, hardened debian, clean UI, comes with Encryption Wizard (http://www.spi.dod.mil/docs/ewmanual.pdf), most go-to distro for accessing your bank account from an unsecure computer, basic set of office tools and programs, partial XP theme that doesn't scream its linux
Cons: No anonymity
Online use: depends, some anonymity might be achieved through public hotspots that also dont record with cameras
Offline use: best candidate hands down

2. Tails 1.1
http://distrowatch.com/table.php?distribution=tails
Size: 1GB
Created by: ?
Purpose: Instant magic solution to privately browsing the web via Tor, or accessing hidden services
https://tails.boum.org/
Pros: encrypted persistence, built in Tor, i2p, basic set of office tools and programs, PGP, privacy centered, optional full XP theme
Cons: heavily relies on Tor which can be compromised, comes with shitty defaults like enabled javascript, always gets patched revealing previous fuckups that may deanonymize its users (browsed i2p in 1.0? sorry, it was broken and unsecure but we fixed it in 1.1 ;-))), nowhere near ready enough to be trusted with anything serious
Online use: with a prayer
Offline use: good to go

3. Liberte Linux
http://distrowatch.com/table.php?distribution=liberte
Size: Under 700MB
Created by: anonymoos skids
Purpose: serious COMSEC
Pros: hardened gentoo, clean ui, basic office programs
Cons: dead, outdated kernel, most likely filled with hundreds of exploits, huge attention grabbing anonymoos man wallpaper/lockscreen
Online use: you will get fuckoed, guaranteed
Offline use: probably ok

4. Whonix
Size: 1.3GB
"I don't see the point in a VM if you want anonymity. Your external OS is prone to leaking out information, and thanks to the fact that the VM is running inside an OS on your HDD you could be leaving behind shit you don't want to. Obviously there are ways to tweak an OS to make a VM safe, but it's a lot less riskier and a lot easier to just use a LiveOS."