When comparing Slackware vs ChromeOS Flex, the Slant community recommends Slackware for most people. In the question“What are the best Linux distributions for an old machine?” Slackware is ranked 10th while ChromeOS Flex is ranked 39th. The most important reason people chose Slackware is:
Uses stable, plain-vanilla packages from upstream.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
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
Pro Lightweight and fast
This is basically just Chrome OS which already runs on Cheap chrome books. It works well for web browsing and file storage on low end computers.
Pro You can try it via bootable USB
Cons
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.
Con Limited hardware support
There is a list online of about 100 or so computers that officially support Cloud Ready, but it can also work on a laptop not on that list, results may vary.
Con Only really meant for web browsing
To use the software, you need to have a Google account and log in. Because it's meant for web browsing and researching, you won't find software like Steam, Office, Adobe Photoshop, Aftereffects, etc; or even a 3rd party browser other than Google Chrome.
Although there are plenty of alternative web browser online, and in the Chrome Web Store, which is still supported by Chrome OS.