I used to use Debian with a minimal openbox setup.
Been using openSUSE since 12.3, here’s a few main reasons i’ve stuck with openSUSE.
Latest stable software/packages
***I think openSUSE is in a really sweet spot when it comes to offering the latest software while remaining stable. This was one of the important goals for 12.3 if i remember correctly, 12.3 and 13.1 have definitely delivered 
Also if you for example want the latest libreoffice or a newer version of another, just head over to http://software.opensuse.org/ and do a quick search & chances are you will find a repo containing the program version you want or newer.
** This is one thing i really like over using Debian. With debian if i wanted a application to be installed or a newer version of a application, I either had to look for a backport, switch to testing or install the deb file using aptPreferences and just pray it works. I think openSUSE does a far better job when it comes to being able to mix various repos and software, with debian i kind of got the impression that if isn’t in the official repos then you’re gonna have a hard time installing and managing the software you are wanting to add.
Best desktop + Best KDE implementation
For ages I never liked KDE or the plasma desktop when i first started getting into Linux. I would use Gnome 2 on ubuntu then Linux Mint, then i moved to trying out xfce, lxde, and then settling on a minimal openbox/tint2 desktop.
Anytime i would decide to try out a distro that had KDE, it would often give me errors, which would often make me think “i dont remember having this issue/error with Gnome2 or openbox” then i would quickly run back to whatever i was using before trying KDE.
However after using 12.3, KDE is my favourite dekstop environment and dolphin is also my favourite file-manager. I think Gnome3 has ruined it for the Gnome users, who all mostly seem to be using xfce, cinnamon or MATE now anyway.
openSUSE has always had the best KDE implementation out of all the distro’s IMO and 13.1 with KDE has been the best distro i’ve ever used.
***SUSE Studio
I really think SUSE studio doesn’t get enough attention that it deserves. I think it is a really smart idea, being able to start with a openSUSE or SLES base, then adding your own repos, uploading your own RPM’s, choosing what packages you want or dont want then downloading your appliance as its called into various formats (CD/DVD, virtual, cloud etc)
I’m the type of person who will try to have one application for one use. For example i use Clementine for music, VLC for video. Any other video or audio player i remove unless it is required by another program.
So it’s great to think that if i wanted to, i could just login to SUSE studio, set up and choose the packages i wanted, then just Download a ISO ready to copy over to a USB
***Out-of-the-box support
Out of every machine (desktop, laptop) i’ve tried openSUSE on, it has always detected all the hardware. It works great on my desktop, it also worked perfectly on my netbook, didnt have to download any drivers or some random script/package someone made, like i had to do for debian to get the touchpad working. Laptops as well, everything was ready to use as soon as i logged in.