I use both.

My home runs pfSense from before I knew about opnSense. It does everything I need and was OK to set up. I run a few VPNs mainly as well as have it NAT firewalling, HAproxy and few basic things like that. Don't use much in the way of pfBlockerNG. I could never find a decent bandwidth counter to simply log incoming/outgoing traffic by IP (something like ntopng). I could never get traffic shaping working nicely but that's not really pfSense's fault unless it was the confusing GUI. Running it on a fanless Chinese Celeron 1037U router type appliance.

We have a pro grade XG-7100 Netgate appliance running pfSense in our office. Again we haven't gone close to stretching its legs but it does the job. It's reliable. I doubt I will ever see support for SFP copper adapters which they say is an Intel software issue. To be fair they do declare it won't work, but in the same breath say it's a software issue i.e. fixable.

Finally I have a VPN server that runs on a cloud VPS. There I decided to try opnSense. Mainly it's the centre point for the above two plus 4 or 5 other users to connect to our LAN. It's also an IPSEC endpoint for our M2M SIMs. Originally it was set up as our serviced office was behind a NAT firewall and didn't have a routable IP. So it basically became the centre of network and gave us a publicly routable IP for $4/month.

Sooo.... if I ever had to reinstall my home machine from scratch which is likely as the HD I'm using is dying, I'd almost definitely want to go with opnSense. UI is definitely a nicer place to be and from what I see it will do what I need and as noted seems to get much more frequent updates.

Main thing though with a reinstall on either is it's very easy to reload your config with all settings in one. So that kind of locks me into pfSense in that I don't have to do much work.

Netgate/pfSense guys' attitude really turn me off too. The AES debacle clearly backfired on them significantly for one. And seems they may have backed down on that. The web page they created discrediting the opnSense guys took the cake. They shot down my mini review of the Celeron I bought above, so I didn't bother finishing it off.

Speed wise they'll be largely the same I expect. General reliability is more hardware related from what I can tell. Get Intel NICs if you can for either as they are generally just better supported than Realtek et al.