As someone who uses CentOS & Red Hat at work and Ubuntu and Debian
everywhere else, I'd have to say that yum and its distros is still
far, far behind APT and its distros.  Part of that is the design of
the tools themselves, part of it is their default configuration (yum
insists of re-downloading the package cache for EVERY SINGLE thing you
do - really?!?), and a lot of it is the quality control of packaging
and repositories by the distribution maintainers.  For instance,
Debian and Ubuntu have FAR more packages in their repositories, and I
only very rarely have to use a PPA or compile something myself.  With
CentOS and Red Hat on the other hand, I can't even get a useful LAMP
system up without adding at least one third-party repository, and the
software we ship at work requires two or three.  Furthermore, the
Debian family does a much better job of segmenting packages into
smaller pieces, meaning there are more packages, but you only have to
install what you really need.  I frequently find in RHEL-land that to
compile something my build dependencies involve installing some
massive package and a whole bunch of totally unrelated stuff, just
because some library wasn't properly split off from an overall
application framework or something.

Now, yum is certainly an enormous improvement over manually fishing
around for individual RPM files, and I applaud the developers for
coming up with it, but the combination of APT's design and the far
superior strict maintainer ethos demanded by Debian (and thus passed
on to Ubuntu) will be keeping me solidly in the Debian/Ubuntu family
for everything I have a choice in for the foreseeable future.

 - Tony Yarusso