What does top quality mean? Well to me it means that best of breed software is included in the distro, like LibreOffice, Mozilla Firefox, various development tools like Eclipse and NetBeans. It also means that when you attempt to install a package, the package and its dependencies get installed without any problems, like running into missing dependencies or version conflicts. A good quality distro also should be easy to keep up to date by either running graphical or command-line update tools like yum or apt. Fedora 17, Ubuntu 12.04, and Linux Mint 13 all meet these quality requirements in stellar fashion.
The next thing that's important to me is the choice of graphical user interfaces provided in the distro. This is somewhat less important since it's fairly easy to install additional desktop environments, but it's real nice to have your favorite desktop installed right out of the box, which usually means that a little extra spit and polish was done to make it look really good. The main choices here are Ubuntu's Unity interface, Fedora's Gnome-shell, Linux Mint's MATE or Cinnamon interfaces.
Mint's MATE interface is based on Gnome 2.x, which was probably the most popular Linux desktop of all time. The Gnome project has ended further development on Gnome 2.x, so the Mint folks took over development and continue to develop under the MATE banner. The Cinnamon interface is Gnome 3.x-like with various extensions that are unique to Mint. Both MATE and Cinnamon are beautiful interfaces, and I can see why many people choose Mint as their number one distro.
Linux Mint 13 installs a full suit of popular software by default, including LibreOffice, Firefox, Gimp, and others, so that the user has basically everything they need right out of the box. There's not much you need to do after installation other than go straight to work.
The same is true for Ubuntu 12.04. The difference is that the default desktop environment in Ubuntu is the Unity interface, which I hate. It's not that it's unusable, I just find it annoying. The window menus have been moved up to the top-of-screen menu bar, disconnected from the window itself, and sometimes the first menu item is so close to the upper-left hot corner that you accidentally trigger the fly-out menu when reaching for a window menu item. That's enough to put me off, although I suppose if I lived with it long enough, I might get used to it. People do, it's supposedly the second most popular distro after Mint.
Fedora 17 uses the Gnome 3.x Gnome-shell interface as the default, which is my favorite. Admittedly it took me while to warm up to Gnome-shell, but I like it now. Unlike Unity, MATE, and Cinnamon, it's an open standard that is available on a wide variety of Linux distros, you can install it on Ubuntu and Mint, and as such, any of the three distros can be setup the way I like.
Fedora needs a bit of tweaking to get it looking the way I like, I don't like the default Adwaita theme, nor the black on white terminal colors. So, it takes me a few steps to get Fedora looking the way I like. I've documented the steps I take in my post: Good Looking Fedora Tweaks. Gnome-shell does require decent 3D-capable video hardware, if your video card is too old, Gnome-shell will fail to load and instead Gnome's fallback mode will appear, which is a Gnome 2.x-like interface.
Prior to Fedora 17, Gnome-shell would always fail to load when running Fedora in VMware Player. This is often how I run various flavors of Linux for evaluation. However, they've seem to have fixed that problem. Fedora 17 now successfully loads Gnome-shell in VMware player. It's not 100% perfect, the upper-left hot corner is sometimes hard to activate, since when the mouse touches the top of the screen, VMware player interprets this as the user trying to access it's menu bar. You can get around this by just clicking on the Activities item instead of trying to bump the corner.
Fedora's Live DVD installation is less than a full install, which doesn't include LibreOffice, Gimp, and various other mainstream tools. This means that the download is smaller, as is the disk space used after the install, than the default Ubuntu and Mint installs. You can then install whatever tools you actually use, and end up with less disk space wasted. This isn't a big deal, all three distros use up very little disk space compared to a Windows install.
The choice of distro ultimately boils down to personal preference. End-user Linux distros have matured to the point where they are easy to use for the average user, and I'd recommend trying all the popular ones to see which ones you like. Right now I'm typing on an old laptop with a 2 GHz Centrino and 1.5 GB of RAM that is setup to dual boot Fedora 17 and Linux Mint 13 Cinnamon.