BSDs are very interesting, I highly recommend checking some of them out. I think the most compelling case for them is the very tightly integrated kernel & OS which is largely decoupled from the user-space packages. I have completely hosed my Linux installs to the point of being unbootable a few times (to be clear, it was my fault every time!) by making mistakes with the package manager, but this isn't really possible with BSDs since the core operating system uses a completely separate method of updating and patching.

The other thing to keep in mind is that the systems are brutally minimalist. As in, Bash is considered a "fun bonus" rather than the core part of the system that is installed in /usr/local. That can be a substantial turn-off for some who see it as archaic or old-fashioned, but there's something to be said for the "stability" not deprecating such an old piece of software :)

Something you will probably appreciate is the consistency and documentation, even with little things like manpages. Every detail is ironed-out and perfected in a way that we're not really used to as Linux users.

There are some good guides out there for installing & configuring OpenBSD on an old laptop, and it's absolutely worth a try. It's without a doubt simpler and lighter than any mainstream Linux distro, and frankly just really fun to play with!