As with most Linux users, I've used more than my fair share of distributions. Fedora, Debian, Slackware, etc. The list could quite possibly go on for a few paragraphs if I were to count all the iterations of each distro I've touched. Despite the many variations of distributions in the wild, by far the one with the most hype is Ubuntu. Why? It's more intuitive than most distributions, and it usually has better hardware support thanks to the inclusion of proprietary drivers. The interface is especially polished, and the community support for the distro is massive. Since it's based on Debian, it makes use of one of the most efficient package management systems available on Linux.

So what does all that mean? Ubuntu is the best Linux for a complete Linux newbie to try. Not only that, but it's targeted market is aimed specifically at the average user, so it comes with all the flashy effects and cool gadgets that you'd want it to (compiz, for example)
But for those of you who have used Linux before (and more specifically, Ubuntu 8.10), here's some of the more exciting features coming to Ubuntu 9.04 Jaunty Jackalope.
Gnome 2.26
- Improved Multi-Monitor support
- Outlook/Exchange Support (Import your mailbox easily, or connect to Exchange servers!)
- Media Extender functionality (Play your videos from that extender you bought!)
X.Org 1.6
- Improved graphics card support
- New free / open source drivers added
- Improved stability
Linux Kernel 2.6.28
- New GPU Memory Manager (Translates to better frame rates during graphics acceleration)
- EXT4 Filesystem support
- Improved Memory Manager
Other features
- New style for notifications (Notifications caused by receiving a new instant message, for example, are handled differently. Click for example)
- Dramatically improved boot performance (I've heard Ubuntu 9.04 boots in 21.4 seconds on average)
- Server edition: Easy creation of Cloud Computing environment through Eucalyptus
- Improved Suspend/Resume support on laptops
If you're interested in checking out Ubuntu 9.04 Beta, you can get it here. Remember, you don't have to install Ubuntu to try it out! Once you've burned it to a CD, you can pop it into any computer that supports booting from CD, and you'll be presented with a Live OS (OS running from CD) that is fully functional.
If you try the beta, leave a comment and let us know what you think of it!