Linux Distributions

Are there any good non-Slackware distributions left?

Systemd is well designed. It was conceived from the top, not just to fix bugs, but to be a correct implementation for the base system services.

Systemd makes the boot process much simpler, entirely removing the need to specify dependencies in many cases thanks to D-Bus activation, socket activation, file/inotify activation and udev integration.
Systemd can handle the boot process from head to toe, without needing to use any of the existing shell scripts.
Systemd is straightforward. The command-line interface is probably the best existing for service management. The unit file format (like .desktop or “ini” files) is completely declarative, can be parsed using standard tools, and is a breeze to maintain.
Systemd unit files, unlike SysV scripts, can usually be shipped by upstream, or at least shared with other distributions (already more than 1000 existing unit files in Fedora) without any changes, the Debian specifics being handled by systemd itself.
Systemd is incredibly fast (1 second to boot). It was not designed with speed in mind, but doing things correctly avoids all the delays currently incurred by the boot process.
The transition plan is easy, since existing init scripts are treated as first-class services: scripts can depend (using LSB headers) on units, units can depend on scripts. More than 99% of init scripts can be used without a modification.