People here are linking to pfSense's past misbehavior wrt OPNsense. I used to use pfSense knowing about that but not caring. But what motivated me to switch to OPNsense was much more basic:

- https://www.netgate.com/blog/announcing-pfsense-plus

- https://www.netgate.com/blog/pfsense-plus-pfsense-ce-dev-ins...

If you're using pfSense CE you're using an EOL product, so you should move to OPNsense just for that reason alone.

Those two posts try to convince you that CE is still relevant and will still get releases, but read carefully and you realize any changes to CE will either be by third parties or those that were part of the base FreeBSD system and thus were upstreamed to FreeBSD anyway. All the actual development work will be for Plus, and the design of Plus is sufficiently divergent (UI backend rewritten from PHP to golang apparently) that you can't backport the work to CE either.

Plus will be free for home use (and hopefully remain so), but won't be open source. Not that CE is all that open source either, but at least you can read and modify the PHP scripts in your installation.

Another reason people stayed off OPNsense was that it was based on HardenedBSD instead of FreeBSD, however that changed a few months ago so that should no longer be a concern.