I too would be interested in the answer. From my perspective, Debian is the server Linux distro par excellence, and in my experience the folks who choose Ubuntu have been devs who don't actually use Linux (e.g., the sorts who develop on a Mac or in a VM rather than on a personal Linux system). It's not really fair to Ubuntu, which is decent enough in its own way, but I tend to consider the choice of Ubuntu to be a bit of an architecture smell.
I'm honestly interested in what the valid reasons to prefer Ubuntu over Debian (particularly on the server side) are.
Newer packages, sane LTS policy, easier to get non-free firmware/drivers going (as in, the default CD comes with them), seemingly more support from third parties.
They're both pretty awful due to their automagic(al tendency to break down in mysterious ways), but if I have to choose, I'll go with Ubuntu.
Disclaimer: My main box runs Gentoo and I own no Mac machines, if that changes anything in your vision of Ubuntu users.
Those two are in opposition: Debian (generally) has new-enough packages, but it's stable, which is what one wants on a server system. Meanwhile, Debian's LTS story is better than Ubuntu's: just upgrade, and know it will work.
> easier to get non-free firmware/drivers
But how often is that needed for server systems? And of course, there're the ethical & engineering issues with using proprietary software in the first place.
> seemingly more support from third parties
There is that, but if we all wanted more support from third parties, we'd have stuck with Windows, no?
> They're both pretty awful due to their automagic(al tendency to break down in mysterious ways)
I've not experienced that with Debian in a long time. I used to have issues with Ubuntu, but I don't think that they were generally all that bad. Better than what I used to experience with Macs and Windows back in the 90s, anyway.
This is a leading word. As is a lot of that paragraph. For many tools some companies use, Debian certainly is NOT "new-enough" with many package choices. Nor is Ubuntu inherently NOT "stable" - and still trails a little behind the leading edge. As for upgrades, I've watched many a server upgrade seamlessly from 10.04 LTS to 12.04 to 14.04. I'm sure there can be and has been many a person, many a thread who've not had seamless experiences. But the same applies for Debian - heck, even the release manual has a section entitled "How To Recover A Broken System" with reference to system upgrades.
"non-free firmware/drivers"
How often needed? In this article alone, IPMI, BMC, RAID, BIOS.
"And of course, there're the ethical & engineering issues"
This is a derailment. What exactly are the ethical issues for a closed source company in using other proprietary software?
I'm by no means an Ubuntu fanatic. It has its share of issues, absolutely. I have everything from FreeBSD to Debian to RHEL to OmniOS to administer, and they all have strengths and weaknesses.
A better question, in my mind, is why they'd choose Ubuntu over CentOS or RHEL, since they're running on Dell hardware, and Kickstart is far, far superior to Debian/Ubuntu's PXE install (and preseeding is awful to configure). My org went through a lot of pain because of this choice (which preceded me) and I'd hate for anyone to go through what I went through.
Also Dell's maintenance tooling barely works on Ubuntu at all; they don't even officially support their OpenManage stack on it. And forget about online firmware upgrades.
CentOS is a turd of a distribution, I'm certain the only reason it has any marketshare is because it's the only supported "free" OS for cPanel/WHM which a lot of web hosts provide for non-technical customers.
