I switched to Debian lately and i think it will become my preferred distribution.
I started with Slackware, then an LFS and then Gentoo. I never found them definitive for me.
I used Slackware by compiling sources most of all, then i didn't see any reason to continue using it.
The LFS came since my new PC as a test, and as long I could maintain it I had no problems and had fun with it.
I then installed Gentoo when i got my first DSL. But the updates are slow for lack of testing, I'm on an amd64. I tried to contribute someway but for the time I've been using it I never seen a open and innovative development (not in the sense that it wasn't friendly). And also, I've seen many developers leaving the project.
In other words, I "almost" used always source-based distribution. All the time I tried other binary-based distribution also to change my way of linux-life, like OpenSUSE, Ubuntu, Kubuntu, Foresight, and so on but no one satisfied me.
Then i wanted to try Debian, hoping it was different than Ubuntu. And in fact it is!
What I like of Debian is it's very high QA, how new users deal with bugs, how stable it is, how the BTS work, how the packaging works (eventough there are lots of useful tools I still don't know), the rapid updates, the security.
The thing I dislike from other distribution is that they release new stable versions but that are not so stable at first. For example i had troubles with the package manager with both Ubuntu and Foresight. Boot problems with Ubuntu, several crashes with Foresight, and so on.
But, I don't want to say Debian is now my preferred distro (I'm still afraid of binaries), but this is the good way and hopefully the last choice. Go Debian!