This discussion focuses on the comparison between OpenBSD PF and FreeBSD PF. There are claims that one or the other version of PF has fallen behind or not kept up with improvements, but these claims are garbage. The developers of FreeBSD PF work closely with OpenBSD devs and both projects want to work together. However, the kernels of OpenBSD and FreeBSD are different, with significant differences in locking models and memory protections. Therefore, it is not as simple as pulling code from OpenBSD into FreeBSD. Despite differences, the constant competition to achieve peak performance benefits everyone. The PF syntax is considered the most approachable in all of open source Unix.
https://mwl.io/archives/23127