I haven't found any that are that similar. PFSense is far better than any commercial SOHO firewall. In fact it rivals all commercial offerings in my mind. I've seen both WatchGuard and SonicWALL top of the line models crumble under a 20mb load that was a couple years ago. Cisco PIX is stable but far less intuitive than PFSense.
Areas where PFSense excels beyond other commercial firewalls.
Intuitive GUI
Feature Rich
Simple to Upgrade
Best backup and restore
Backup file is intuitive relatively easy to modify manually.
Commercial Support is available and high level.
Developers are generous and will respond to ideas, and questions.
Customizations and new features are in reach even for the modest budget with a bounty.
Leverages the power, security, stability, and maturity of the FreeBSD operating system.