Home:
Arch with Cinnamon... and I think GDM? on my tower and main laptop, a broken Debian testing (seems to boot but never shows the login manager) with Gnome 3 on the netbook.

Work:
Arch with Cinnamon... and I think GDM? on the main, Mint 17 (Cinnamon) on two secondaries. (Android on a rarely used 7-inch netbook, if you want to include that in "Linux distros".)

...so that's what, three distros and as many configurations (excepting hardware/driver differences) on six machines.

Primary system: Debian Jessie/Testing with Cinnamon, but I equally like KDE, Enlightenment, and LXDE.

Home server/HTPC: Debian Wheezy (will upgrade to Jessie) with LXDE (likely changed to Kodi/XBMC in the future).

At work, I've converted an old box into a OpenMediaVault server with Debian Wheezy.
And when I can get away with it, I dual-boot Mint LMDE with Cinnamon to gently introduce people to Linux and show them it's really not that scary.

Deep down, I'm an endless tinkerer. So at some point I will play around with Fedora, CentOS, Arch, and Gentoo mostly to experience them and see if there are things I can learn there.

Not part of the original question, but spurred by my comment of tinkering:
My current "projects" are to understand Wine better, and how people figure out what settings work best for each game (I'd like to contribute if possible, but my background may not lend to that). Find more sure footing when compiling software. And to Keep tabs on Debian developments (currently following the systemd adoption... **rubs temples** wow).


Edit: Formatting

Short answer: I've been using Ubuntu for the last 7 years.

Mint 17 Cinnamon is the one I like the most for sure. As someone who likes Windows, but doesn't like how MS handles it... Mint is a very close Windows experience without the issue of having to actually use Windows.

As a standalone window manager, openbox includes almost no user interface. The only default item openbox includes is a right click menu, which is configured in an xml file. Any UI after that, you build from other packages.

I have conky displaying in a dzen2 bar as a status bar. plank is my dock / taskbar.

I have dmenu-run configure to appear at the botom of the screen on win+r keyboard shortcut for a full system menu. My menu xml for the openbox menu only contains my frequently run programs.

The other thing I love about openbox is how easily configurable shortcut keys are. I have a bunch of my must-have apps configured to shortcuts (ie. win+c=chromium, win+t=thunar etc.). I also have a set of keyboard shortcuts to do some window placement (ie. win+z->a=left half, win+z->q =top-left quarter, win+z->w=top half etc.).

I've attached a screen shot.

Yeah that sounds a bit too much like work to me :P
Now.. is that your background just because it's interesting.. or also because it reminds you of boobies?

After long pause, I got a laptop and played with Arch Linux for a while. It has definitely very, very well explained guides however I realized I wouldn't get to the point I wanted to start rebuilding a web's code into object-oriented for a long time (because I would be still playing with the system), so I replaced it with the latest LTS version of Ubuntu.

I was pleasantly surprised Aegisub got Linux support and Steam's releases became playable after one click. Nothing else changed much.

I put my bet on Slackware ;)

As for me, I’m in an everlasting love story with my Debian Sid.

That's right. :)

I moved to Mint 17 from Vista. SO FAST. Holy crap I can boot it and start playing within a minute. This is magic.

Parted Magic.

Ubuntu 14.04 LTS with Unity cause I like the Dash features so that I don't need to use menus and its very fast.

LXLE 12.04.5 32bit with (LXDE) [64 bit users can install the new 14.04.01]

Lighter than Windows 7/8, beautiful, and still very powerful and full featured.

http://lxle.net/

Linux Mint at the moment - and for a good long time (still on v13). Want to switch over to Manjaro eventually - the rolling release philosophy of Arch with a bit less of a 'DIY' everything philosophy behind it.

I really dislike having to re-install a full system frequently. It was a pain having to do it yearly (or there about) on Windows and I don't like it with Linux either - which is why I always stuck with the long term support versions. Rolling release just plays nicer with how I use a computer.