Claudio has designed some art which describes the history of Debian GNU/Linux structurally and with some statistics. It is interesting to see how it has grown. There is some debate about use of the “testing” branch by ordinary users. I am on the fence on that one. We are mid-way through development of Wheezy and the testing branch is very usable for me. I don’t see why it should not be considered comparable to some other distros that are released to the public. I don’t think it is fair to deny users “testing” for a year or more longer. On the other hand the rate of updates to testing during the debugging phase is a burden for ordinary users.
I recommend Debian GNU/Linux. It’s a cooperative project of the world and it works for all kinds of people.