One Mark of a Good Distro
Everyone has their favorite distro. I try to remain neutral, but in Linux it's hard to hide your true feelings sometimes. Of course, all rivalries are supposed to be in good humor. Needless to say, I've tried a lot of distros. Some I've used a lot longer. I've found there are a few basic characteristics that make some distros better than others.
To me having a large and up-to-date repository is always a plus. In fact, it's probably one of the most important features. I like a distro that I can equo, urpmi, or apt-get me whatever obscure piece of old software that I love. The less of these I find, the less I like the distro. Magiea is doing pretty good, but it's missed one or two*. Sabayon always had whatever I wanted - almost always. I'm sure there were times I might have been disappointed, but I can't remember any.
Mandriva used to well stocked as well, but I don't think anymore. PCLOS was always pretty well stocked too, and users have the added advantage of asking for packages from the small (sometimes very small) team of developers. openSUSE's is okay, but I don't like having to go hunting for proprietary software. I prefer those who offer them in their package manager.
Linux Mint is really well stocked, but half their inventory comes straight from Ubuntu. Which is a good thing. And which is the main reason Mint is better. The value added from Mint's contributions is evident in the money they make. I'm not really sure how their revenue compares to other distros, but for a small independent team, they seem to do okay. (They publish their donation and subscription receipts each month. Something other distros don't do either.) And that my friend is something especially hard to do in Linux. Most developers make little or nothing (unless they're on one of the big guys' payrolls - which is good work if you can get it). I get the impression Mint users are quite happy.
A lot of distros offer a pretty face and ease-of-use, but if their repositories are small, so is their following.
* But we have to cut Mageia some slack cause they are really just getting started. This is their first release and I stick around because its KDE (or more specifically Kontact, or even more specifically KMail and Akregator) is really stable. I've had maybe one Akregator crash since version 1 was released. The way KDE life has been for the last couple of years, this is a nice little oasis.