Unless you have some reason not to you should just run Ubuntu. It's by far the most popular desktop Linux distribution, which tends to make your life easier. I've been using Linux as my desktop for 15+ years, so I've run lots of distros, but I'm using a stock Ubuntu 13 on my machines. It works, gets out of my way, and let's me get work done.
According to distrowatch, the order is:
1. Linux Mint
2. Debian
3. Ubuntu
Me, I prefer Mint with MATE because with just a few patches the screen is much more readable than any other distro and it is based on Ubuntu, so I have something to fall back on.
Otherwise I would use Arch.