I use both apt, pkg-ng and yast/zypper/rpm. Both apt and pkg-ng work well. Apt has --really-long-switches that are easy to remember but not quite as many shortcuts for them. Sometimes pkg-ng is annoyingly upgrading itself but that's it. Rpm is rather annoying but zypper and yast make things easy to manage. I remember the old RedHat 4.2 days when I had to work with rpm exclusively; it has an inconsistent CLI with weird command line switches.