"Best" doesn't really exist. Regarding "best for you", I would say Fedora, SuSE (harder to install the latest version, though, unless you pay for it), or Mandrake.
horndude is probably gonna tell you to go with Slackware. I'll tell you that right up front.
There is nothing wrong with Slackware, in fact, I like it quite a bit. But what distro you use is up to you. Look around and pick the one that appeals to you the most.