with nothing better to do (with my time or bandwidth) I have, in the last 2-3 weeks, downloaded the following for personal testing.....
(all versions being 32 bit, reasons as per my previous post)

Ubuntu 11.10 (am already running this wanted a fresh install on my new HD)

Fedora 15

Opensuse 11.4

LinuxMint 11

Linux Mint is a Deb based Ubuntu derivative and offers a nice clean interface. installed with Gnome (2 not 3) and found it to be not that different to Ubuntu, in real terms.

Opensuse is a stable (dare I say commercial level) desktop OS and works well with KDE or Gnome, despite having it's roots in KDE as the preferred UI.

Fedora 15 is "bleeding edge" and offers istself as one of the first to come with the Gnome 3 desktop.

Ubuntu - well, it's by most references, the No 1 Desktop Linux OS. Is easy to set up and install, provides an abundance of software (and additional repos everywhere) allowing for a huge selection of applications and customisation, be it media-centric or other.

I started on my journey with Red Hat, moving to Mandrake (Mandriva) and then on to Ubuntu, via a whole host of others on my "doesn't matter if I break it" machine, before finally settling on Ubuntu with Gnome.

I can say I'm not particularly overwhelmed with the Unity Desktop that ships by default and for some reason have always had niggly issues with knetwork manager in KDE with my wireless lan at home, thus have resorted to the "Old" Gnome version of 11.04.

LinuxMint seems to be a good, stable Ubuntu variant and I guess the similarities to Ubuntu are what left me a little underwhelmed.... (I confess I like new shiny stuff)

Fedora 15's default Gnome Desktop (3) is nice and clean and offers a different take on Most Linux flavours. It still markets itself as "cutting edge" and remembering the label form my Mandrake/Mandriva days, I'm sure may present some interesting idiosynchratic behaviour, though I didn't find it myself over the week or two I trialled it.

All flavours are developed to a level where their respective package managers will take care of dependencies and pretty much offer up a fully automated install of software. Most offer an easy way to set up repos for non-free/nono-gpl software ala flash, adobe, propriatory hardware drivers (ATI/Nvidia) etc,
Fedora and Opensuse allow for an automated SELinux install right from the installation GUI, which offers all the benifits of security enhanced Linux.

I'd say give any of the above a shot (simply for ease of intall) in their 32 bit live cd variants, and when you find the one you're happy with, give it a shot with 64, if you feel the need or have specific applications that will only run under a 64 bit native environment..

Good Luck