I've been down this path before. I'd argue strongly pfSense is non-trivial and will require significant time investment for most people coming off Unifi stuff to learn the ropes, and should not be considered a serious alternative for most people. They have very different target markets and this is reflected in the software. Unifi is much closer to a "plug and play" user experience in comparison to pfSense. The customization options for pfSense are of-course fantastic.

I actually reversed this choice and am back to using the Unifi Controller again - pfSense is superb in production or more-networking-enthusiast style environments, not so nice for "average" home. I used a 5-ethernet port fan-less Intel Atom box almost identical to the one you linked for my homemade pfSense router while it was running, for that purpose it was pretty good.