Ubuntu and Debian's PHP packages are largely the same.
> I've since convinced [most PHP devs I talk to] to stop using distro-provided packages, in favor of deb.sury.org.
You do realise that Ondřej Surý (of sury.org) is the primary Debian PHP maintainer? The point of his repositories (AIUI) is to allow users to mix and match PHP versions. The downside is that he's one person with (AFAIK) a bus factor of 1 when it comes to security updates. That's irresponsible to use in production.
In contrast, Debian and Ubuntu's PHP packages, essentially provided by the same person, has in addition teams (both in Debian and Ubuntu) who can pitch in when required.
For example, the current package for Ubuntu 16.04 LTS is 7.0.22-0ubuntu0.16.04.1. How does this mismatch 7.0.22 from the PHP upstream project?