Whats the Best Linux OS

The only one I tried was Fedora Core... however, a lot of people like different distros for different reasons. Ubuntu is supposed to be extremely easy to use, so if you're new to Linux, you may want to try that one first.

Any of the newer, popular distros that are "user friendly" each have their perks and shortcomings, but all of them are leaps and bounds easier than even just a few years ago.

Try out each of them (don't need to install any of them, Fedora, SuSE, and Ubuntu all have LiveCD versions, just keep in mind since it is running off of a CD/DVD it is going to be much slower than if it were residing on a hard drive) to see which fits you best. This is the most powerful aspect of GNU/Linux and OSS in general: it is much more customizable and can be exactly what you need and nothing more.

Horses for courses. At the moment you are just getting personal opinions but you have not said what you want to use the system for or what sort of hardware you want to run on. Give a few more details and it might narrow down the search.

As your question stands Ubuntu (well supported / documented / useable) would be my suggestion. Run Automatix on it to get the sound and video up and running along with Java and a few other bits and you are mostly good to rock.

Also to add to the suggestions of liveCD's (one of the best ways to look at a new distro) is that you can have a play with an install under something like the free VMWare Server product.