If you have never used Linux before, and are otherwise used to how MS windoze does things, then Ubuntu is the best choice that I am personally aware of. I have never tried Arch Linux, but I have tried Red Hat, Gentoo, Peanut, Slackware, Suse, DamnSmall, and a number others that I can't recall at this time. Ubuntu is, by far, the most like Windoze with the least need for command line administration. I, however, prefer Gentoo. Runs like a scolded dog. I was playing Stargate SG-1 videos on a 486-66 with 64 megs of ram, way back. Everyone I ever talked to thought it was impossible, till I showed them it could be done on a tweeked Gentoo install with only BlackboxWM running on a video card framebuffer.
+1 on what craighto says about Ubuntu and Gentoo.
So far I've been using and admining Slackware, some local Red Hat flavour, Debian, OpenSuse, Gentoo and Arch Hurd (not Linux) and a few more.
For home use personally I much prefer Gentoo, because it's a rolling release and you can tweak the living crap out of it. Also it's a dream to admin, once you get used to it.
But at the end it boils down to what you want and what you need.
Maybe playing about with a distro chooser could help you decide:
http://www.zegeniestudios.net/ldc/
http://polishlinux.org/choose/quiz/