Well what? Slackware is your best choice most likely. It's been claimed by most to to be the "most" unix like Linux distribution.
As someone said before "My distribution is in all ways superior to yours...", so in this case - I'd vote for ArchLinux. It also has BSD style init (as does Gentoo and Slackware), but it also has cool source/binary package management and it is easy to build Arch packages by yourself. Arch also uses the same philosophy as Slackware - KISS (Keep It Simple Stupid).