Ultimately it doesn't matter what you choose because they all do the same jobs overall, they all have unique strengths and weaknesses, and no matter which one you choose you will probably end up switching a few times anyway. I have used installed and used Slackware, Ubuntu, Gentoo, and OpenSUSE over the years (and tested several others via VM's and boot disks). I am back to using Ubuntu now, and I have stuck with it for a year or two this time.

The great thing about Ubuntu (especially for noobs) is that there is a TON of information out there on the web. You can find solutions to problems with nearly any distro through google, but Ubuntu just has a kazillion sites out there with users posting solutions to problems. If you want to get started learning the ins and outs of linux, then install ubuntu and try to do your daily work with it. Switch to opensuse in a few months if the bug strikes you. Once you get comfortable with the system, install some VM software (I like virtualbox if you don't plan to leave the VM's running as unattended servers) and play with other distros.

Whatever you do, just jump in the pool and start swimming or you will never even get wet.