Canonical Ubuntu 8.10
Anyone who knows anything about Linux has heard about Ubuntu. It's easily the most popular desktop Linux around. There's a very good reason for that: Ubuntu 8.10, a.k.a. Intrepid Ibex, is easy with a capital "E."
The GNOME-based interface is easy enough to use, but Canonical backs it up with a strong community. If there's something you want to do on Ubuntu -- anything at all -- chances are you can find the answer on one of the Ubuntu forums such as the Ubuntu Forums and the Ubuntu Community Team Wiki. This support isn't a feature per se, but it shouldn't be underestimated. An open-source truism is you can always find help online -- well, sometimes you can. When it comes to Ubuntu, though, you can almost always find help.
Of course, you may not need that much help. For example, with the new Network Manager 0.7 you can not only easily hook up to wired and Wi-Fi networks, but you can also now easily connect with 3G access points. I used an AT&T USBConnect Quicksilver USB device on my ThinkPad to get a 3G connection, and it worked like a charm. Since Network Manager treats all 3G devices as vanilla serial devices that use PPP (Point to Point Protocol) for network connections, it should actually work with more 3G devices than Windows does.
Another real plus is that Ubuntu 8.10 now includes Dell's DKMS (Dynamic Kernel Module Support). This feature will be invisible to most users, but the effect it can have on stability is profound.
DKMS automatically updates and downloads drivers that match your system hardware whenever you update your Linux kernel -- even if your kernel doesn't include built-in support for a graphics card or other device. Get it? With this, you don't need to worry about your system working even if you add in new hardware or your distro updates its Linux kernel.
There are a few things I don't care for with the new Ubuntu, though. The first is that, while you can set Ubuntu and its KDE-based cousin, Kubuntu, to use the older KDE 3.5.x interface, the distro now defaults to using the KDE 4.x desktop. Personally, I find KDE 4.x to simply be not as good as KDE 3.5x, and I know I'm not the only user who feels this way.
I also wish that Ubuntu had included OpenOffice 3.0 by default. As it is, the distribution comes with the older 2.4 version. Getting the new OpenOffice isn't a big deal, but still, I'd just soon not have to worry with this 100MB+ download and update.
So who is Ubuntu for? To my mind, there's no question about it -- Ubuntu is the best beginner's Linux in the land. It's also more than good enough for experienced Linux power users, but if you're just getting your feet wet with desktop Linux, Ubuntu is the Linux for you.