Pentest Distros 2016

Kali: https://www.kali.org/ (Debian based / gnome)
ParrotOS: https://www.parrotsec.org/ (Debian based / mate)
BackBox: https://backbox.org (Ubuntu based / xfce)
Pentoo: http://www.pentoo.ch/ (Gentoo based / xfce)
BlackArch: http://blackarch.org (Arch based / lightweight)
Weakerthan: http://www.weaknetlabs.com/ (Debian based / fluxbox)
ArchStrike: https://archstrike.org/ (Arch based / which you want:))