* Systemd > Upstart in performance usability (for me, at least).
* selinux > apparmor when properly integrated (personal preference, but it sees more active development and feature parity).
* RPMs and debs are basically the same thing except not. I have to say adding repos in Ubuntu is much easier than in Fedora.
The choice of GUI during installation is also nice. I just can't keep putting relations and friends on distros that break on really major updates (like 10.04 to 12.04 for Ubuntu) and that is one of the reasons I run Arch. Problem is Arch has really bad support for MAC and takes forever to set up.