Little things. UFW included by default, so you can set up a firewall without having to wrestle with iptables. do-release-upgrade to handle upgrades, instead of having to work through a list of release notes each time. Nothing earth-shaking, just things that sand down some of Debian’s rougher edges.
Not speaking for the parent, but I much prefer Ubuntu over Debian in this context for the sake of the wider variety of packages from official repos that aren't a few versions behind by default.