In practice, any of them will do. I'd advise you to discard the old versions as support will die sooner. Also consider your skills when choosing: using a great distro when you do not know how to use it is not a good idea.
From now on, I'll answer from the biased point of view of a user who uses a Debian logo as an avatar :) I'd advise you to use either use Debian or CentOS as they are usually the choice for servers. Ubuntu has a huge community and in many scenarios a Debian user can benefit from it as Ubuntu is Debian based. CentOS is RHEL based and the community is not so big in comparison. A good thing about CentOS is that they provide support for each version for about 10 years.
