You know, the best one is the one that will effortlessly detect all your hardware, install the right drivers automatically, and make them work.
This may take investigating three or four distros unless you are lucky and someone with the same hardware as you has posted how to get everything running with distro xyz.
If no kind stranger has done this, I recommend you start with Knoppix, at least to identify the hardware you have. Write these down and save the list to a usb drive. (or a spiral notebook, if you were alive in the mid to late twentieth century.)
With this information start your search or experimenting with other distros and look at their forums searching for your hardware.
Only after your hardware is working should you think about what you want your desktop to look like or what version of what applications you want to use. Except for an experiment with a distro call (then) Mandrake, I have always used Debian based distros. The most popular now is Ubuntu. The for pay one where you will get telephone help setting up your hardware is Xandros. In between is Mepis 8.0.
Should you find what you hear about Slackware based or Red Hat (forget the new name) based distros, interestig, I neither discourage nor encourage you to try them because I have zero experience with them.