When comparing FreeBSD vs Slackware, the Slant community recommends Slackware for most people. In the question“What are the best Linux distributions for misanthropes?” Slackware is ranked 2nd while FreeBSD is ranked 16th. The most important reason people chose Slackware is:
Uses stable, plain-vanilla packages from upstream.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Secure and stable
Pro Large repository of precompiled packages and highly customizable ports
Pro BSD license
Pro Easy to install
Pro Good documentation via the FreeBSD handbook
Pro Customizable
You can customize EVERYTHING as its an UNIX OS!
Pro Stable
Uses stable, plain-vanilla packages from upstream.
Pro Strong adherence to UNIX Principals
Pro Ideal to learn more of Linux
Follows the original Linux roots. It still sees Linux as a free clone of UNIX so the distribution tries to be UNIX-like.
Pro Package management
Uses standard tar archives with shell scripting as packages.
Pro One more distro which is init based
Some users don't like to install systemd based distros because they increase booting and processing speed.
Pro Oldest surviving Linux distro
Besides Debian (which was first released in August 1993), it is the oldest still maintained Linux Distribution and was first released in July 1993.
Pro Super fast
Pro No systemd
Cons
Con Hardware support is lagging
Con Installing with "software source code ports" and software packages can not be mixed
Con Too much hardware is not supported
Con Not for everyday use as a Desktop
Con Not user-friendly
It is made to be KISS (keep it simple, stupid), so you have to do everything by hand.
Con Large size live ISO
One needs to vain 3GB+ data for downloading one slackware ISO.
Con Narrow repos
Doesn't offer the same amount of options as other distros do.
Con Niche/small community
Slackware is its own niche and has a small community.
Con Very slow release cycle
Hasn't updated in 3+ years.
Con Dependency issues
When it comes to dependencies, Slackware shows more issues than many other distros.