Two of the most common and well recognized firewalls, PfSense and OPNsense both support site-to-site IPsec VPN and client, Open VPN and client, and PPTP client. Both also have intrusion detection and prevention in transparent mode. I like that both firewalls offer DNS filtering with any DNS filtering company and also have a network configuration feature with customized configuration that is enabled by a setup wizard.
Two stark differences between PfSense and OPNsense are that PfSense does not allow for quick updates and patches, but OPNsense does. On the flipside, PfSense has two factor authentication that works with a remote radius server, which OPNsense can’t do.
Another feature of each to consider based on your company needs is the dashboard; PfSense has drop-down menus, while OPNsense has its menus placed on the left side. It comes down to your personal preference, but I find that having menus on the left side of a dashboard makes it easier to use because it is organized and navigation is clear. Some people may think OPNsense is harder to navigate because of the messy dashboard layout.
What I like about both options is that they are free to download and use. They also both have frequent updates, with constant updated documentation. OPNsense seems to be more intuitive to use and has a great reporting feature. PfSense, though, seems to have more product tutorials available and also more answers to FAQs that can be easily found online.
Both products have a similar set of features. In my opinion, though, I think PfSense is superior to OPNsense, not only because it has an array of features but also because it has an automatic backup feature that I find very valuable.