i agree, you'll never know which one you prefer till you have tried them.

my top recommendations for linux distros for former windows users are:

Mandrake
Fedora
Ubuntu
Xandros

in that order, though i swithered a bit about which way round to put ubuntu and fedora. all three have their "issues" and none of them is a proper ms windows replacement. i have heard that SuSE have dodgy licence requirements of their users now, so personally i am staying clear of it. the only people i know using it are also capitalists, make your own mind up.

I would also recommend slackware if you are not looking for a windows clone, and if you are interested in learning a bit about linux. unlike debian and gentoo, you can get a working slackware more or less out of the box and then dive into the configuration of it from there.

some people end up with quite unusual favourite OSs though, you'll just have to try a few.