I ended up using tasker, which is less "next gen cron" and more just a full featured cron. It's a single executable, and it doesn't assume that it's running as the root cron job. Ultimately, the fact that it was compatible with the extended crontab format was the deciding factor: it's familiar, all of the jobs are in a single config file (as opposed to systemd, which splatters out timer configs as individual - and rather verbose - config files, across a half dozen directories in the FS), and it is sufficient.