Ok I got your back so prepare to get.... an answer:
The reason why you should chose Ubuntu ( I say 12.04) it's because Ubuntu is backed up by Canonical, you see in order for any Linux distro out there to get updates to be: secured, increase performance.... there must be people out there to do that, Canonical is not just some 21 year old computer geek who is still learning Canonical it's a bussines they know what they are doing so being backed up by Canoical Ubuntu it's more reliable, it's more stable and secured. Other distros are developed by either a group either even one person but not much an Enterprise.
The reason why you should chose 12.04 is because it's LTS (Long Term Support) Canonical will offer updates for this distro for a long time this makes the developers able to make good software for Ubuntu since they have the ensuring from Canonical that the distro is going to be "alive" until 2017.
There are a lot of great Linux projects out there that is just great but really if you look on the market there are really only 3 of them RedHat (for like BIG data centers, big cloud infrastructure)
Ubuntu (more geard toward end user (home user) but also on servers and cloud) and Suse with Suse Linux Enterpise the same for all .
For example really popular software it's available for Ubuntu such as : Skype, Steam, Teamviwer, GoogleChrome and a lot more on the Ubuntu Software Center, Other distros such as Fedora don't come with Steam,Skype you can get them wroking but... not even legal for example Ubuntu has access to legal MP3 encoding and other movie / music formats, again because Ubuntu look towards end-users such us you and me.