I use pfSense CE, and rely on DNS entries to be automatically created for DHCP addresses. That worked fine for more than a decade, until they made Kea the default a couple of years ago (or did they just put a bunch of notices in the interface that old DHCPd was deprecated? It's been long enough that I don't remember).

Anyway, at the time Kea (at least in pfSense) wasn't able to do that, which caused things to break for me for a bit. It's a small thing (and, I mean, totally fair with free software) but the fact that they pushed an update to Kea before Kea (again, at least in pfSense) was at feature parity rubbed me the wrong way and has kept me from using it since then.

(edit: on the off chance anyone cares, I decided to check and it looks like this issue has been fixed as of pfSense CE 2.8.)