They're quite different, but in subtle ways, and sometimes it's not about what they offer but rather what they don't offer.
What they all have in common is that they have great documentation, and they're all very unix-y and all have some virtualization support for linux.
Some things FreeBSD offer are good performance, IME the largest package repository, zfs integration, capsicum and jails. The experience IMO is a bit like Arch, except you'll rely less on a wiki and more on their official documentation.
OpenBSD and NetBSD offer a more "complete" experience like you'd expect from a desktop OS, while at the same time being quite minimal and simple.
OpenBSD focuses a lot on security, and is probably more likely to work with your hardware with fast wifi. It doesn't offer the same virtualization nor security the same type of security as Linux, but instead encourages you to pledge and unveil your applications, which means you lock down each application by saying what it can and can't do. It notoriously removes features from the kernel that are unmaintained and also doesn't include things it considers insecure like bluetooth. It's probably the OS that gives you the most "works out-of-the-box" experience.
NetBSD gives you a full desktop experience as well, but also has some unique security features like kauth, veriexec, extra-hardened chroot and security.curtain. It also offers some cool features like rumpkernels, smolbsd, and is probably the easiest to hack and compile yourself (even cross-compiling is very simple). It has a package manager, pkgsrc, that runs on many other OSes and it's also quite easy to port to new platforms. It's a fun OS to tinker with.