I know I just wrote a long piece about Arch Linux and for most things I've pretty much switched to Arch Linux as my primary, day to day, distribution. In fact, when an Arch Linux issue comes up at work my coworkers call me first. And I suppose it's well earned. But if you were to ask me what my favorite Linux distribution project was, I'd probably say Debian as often as not.
I run a lot of Debian, straight up, unmolested (mostly) Debian Stable. There are a lot of practical reasons for this: it's stable, I have faith that it's going to work and do what I need it to. Aside from keeping on top of normal security issues, the system is stable and doesn't require attention to keep up to date. And, in nearly every case the package manager can be trusted to do the right thing. There are also a ton of little niceties in the distribution: debconf, the management tools for Apache, and the shear diversity of the packages. It all adds up.
I mean, I have gripes with some things that Debian does, but they're always little. I find myself asking "Why didn't you enable mod_rewrite by default? Really?" or "Would it have killed you to include software that was less than 3 years old in this release?" But never "Why is this broken by default?"
With projects like Ubuntu getting press, attention, and energy (and money!) I can't help but think that the outsider might think of Debian as being a bit... put upon? Or not good enough in it's pure form? The Ubuntu folks are pretty good about talking about their Debian roots, and it's totally clear to anyone who really takes a good look at Ubuntu that most of its awesomeness is due to being Debian-derived. Even if that isn't terribly clear from the outside.
I also really enjoy the ways in which Debian has managed to grow and sustain itself, and create something that is so magnificent in scope. The Linux Kernel project is huge, the desktop projects are massive in terms of what they carry under their umbrellas. Distribution projects that start from nothing and control and build the entire stack are, I think, particularly intense because of the shear size of the project.
This of course holds true for all distribution projects, and doesn't make Debian particularly special, I suppose. The thing is that Debian's coverage is massive compared to other tools. Arch provides a great framework for an operating system, and makes it really easy to do a number of things, but there are nowhere near as many packages nor as many contributors. Ubuntu is, by contrast a great project but is mostly a process of "tuning" Debian into a system that's more targeted for specific applications. Again these aren't criticisms, but it does make Debian more of an impressive proposition.
And I guess, because of this, even though most of the time when I interact with a Linux system it isn't actually Debian, I almost automatically categorize myself as a "Debian person."