I've tried both Zorin and Ubuntu, but found Ubuntu to be more user-friendly, and it has a super clean user interface. It's literally for everyone, from those who are new to computers in general, to those who want to go dig deeper by using the command terminal. Ubuntu was my first Linux software, and most of the time I used the terminal because it was pretty fun. In terms of software compatibility, use at your own risk. For the majority of the programs, you can download them at the Ubuntu store, such as skype, IRC, Chrome, etc...but I think in the newer versions today you should have Chrome or FireFox as well as LibreOffice (which is a free and clean alternative to Microsoft Office) so that can save you a lot of time when it comes to installing things you need.
Oh, and don't forget Wine, which is an emulator tool for Windows programs, should you want to install any Windows-only programs on your Linux distro. It will become your best friend.
Ubuntu 14.04 LTS is the latest version, and to be honest I'm very tempted to download it. It looks reeeeeally good.