Slackware is what I'd use if for some reason I couldn't use Debian or Ubuntu.
Asus K55A (Core i5-3210M @ 2.5GHz/8GB RAM/120GB SSD/Intel HD 4000) with Ubuntu 12.10 Beta 2
Compaq Presario C700 (Pentium Dual-Core @ 1.6GHz/2.5GB RAM/500GB HDD/Intel GM965) with Arch Linux and Linux Mint Debian Edition
Non-Debian? Does that exist?
Just kidding, I have used others:
I always liked Mandriva for the looks, but I can't stand rpm/urpmi.
Other than that, I have a thing for minimal distros: DSL, Puppy, tiny core...
I still have a working tomsrtbt floppy disk. It amazes me how much stuff he was able to cram into a single floppy...
Don't eff with The Cult...
OpenSuse, Fedora and Arch.
OpenSUSE and Gentoo.
I would probably have to say for me it would be OpenSUSE 64 bit like 12.2 for now. I like the GUI for the Novell AppArmor configuration which Ubuntu lacks although you can add the Armorforge PPA for similar results. OpenSUSE is a great GNU/Linux distribution for users looking for a more up to date enterprise focused set of tools that also can become a rolling release distribution as well with the Tumbleweed repository. It's a pretty good distribution in general if you can get used to the RPM system and fewer software packages in general. This would be my distant second choice to install bare metal. I am very happy with Ubuntu 12.04.x 64 bit LTS.
I haven't explored many non-Debian based distros for myself, but I looked over my friend's shoulder while he explored a few. PCLinuxOS was a favorite but I think he had some hardware issues with it. Very friendly forums and lots of support and kind to kids (read: they tolerated us, lol). If not for the hardware issue I think he would have stuck with Phoenix, the Xfce edition of PCLinuxOS.
We also looked at SalixOS, which is Slackware-based. It has super duper long-term-support because it's fully compatible with it's parent distro, but nicely simplified and adapted to "casual desktop users." What Ubuntu has done for Debian, SalixOS has done for Slackware: Bring it's parent's awesomeness to us ordinary, technically challenged mortals. It's been dubbed "an OS for lazy Slackers." It ran just great on his aging, modest hardware and was simple enough even for me. If I weren't so delighted with Xubuntu I think SalixOS would be my primary OS.
I have never tried anything outside Ubuntu / Debian. With the exception of Fedora on the university but that was not my own install (student workstations had Fedora/XP dual boot) and I did not spend much time on it.
The main reason is I don't see any practical advantages in trying anything outside the *buntu family right now. Kubuntu has all the functionality I need and is light enough for this hardware (> 4 years old desktop).
"I believe humans get a lot done, not because we're smart, but because we have thumbs so we can make coffee." --Flash Rosenberg
I found my old Red Hat 6.4 CD the other day. Hmmm where's that old 486 CTX laptop gone to.
Try the big 3! Xfce, KDE4 & LXDE!