Linux Mint 7 "Gloria"

Excerpt From DistroWatch.com:

Linux Mint is one of the surprise packages of the past year. Originally launched as a variant of Ubuntu with integrated media codecs, it has now developed into one of the most user-friendly distributions on the market - complete with a custom desktop and menus, several unique configuration tools, a web-based package installation interface, and a number of different editions. Perhaps most importantly, this is one project where the developers and users are in constant interaction, resulting in dramatic, user-driven improvements with every new release. DistroWatch has spoken to the founder and lead developer of Linux Mint, Clement Lefebvre, about the history of the distribution.

Some of the reasons for the success of Linux Mint are:

It's one of the most community driven distributions. You could literally post an idea in the forums today and see it implemented the week after in the "current" release. Of course this has pros and cons and compared to distributions with roadmaps, feature boards and fixed release cycles we miss a lot of structure and potentially a lot of quality, but it allows us to react quickly, implement more innovations and make the whole experience for us and for the users extremely exciting.
It is a Debian-based distribution and as such it is very solid and it comes with one of the greatest package managers.
It is compatible with and uses Ubuntu repositories. This gives Linux Mint users access to a huge collection of packages and software.
It comes with a lot of desktop improvements which make it easier for the user to do common things.
There is a strong focus on making things work out of the box (WiFi cards drivers in the file system, multimedia support, screen resolution, etc).