APT
The reason why APT works so well is that people take a LOT of time and effort in getting it right.
There's NOTHING that apt does that RPM couldn't do.
The problem with RPM is that most people are really quite crap at making them. They don't put the care in to them. And so they depend on things that for your system is in two different RPMs because you picked someone who built the RPM without checking what someone else had done.
The applications can do it.
The users are generally not bothering to put as much effort in as the Debian people.
Which may be a problem with people grunting out software for Ubuntu: if they don't take the requisite care, apt won't work quite so well.