I am not new to Linux, but there are so many distros and I haven't been good about trying them all. For me, a gui is a necessity as I won't spend much time studying code, although I know some and have copied lines to get a piece of hardware or a program to work.

Use the distro you are most comfortable with. You can run server applications on anyone.

Which distro are you most comfortable/experience with? That would be my recommendation.

Ubuntu has the reputation as the most beginner-friendly distro and support forum, here's a link to the Ubuntu Server Guide to get you started: https://help.ubuntu.com/12.04/serverguide/index.html

You don't need to "study code" to function without a GUI----you just have to learn a few commands. I have never set up a server, but I'd guess that one would operate more efficiently if it were not running a GUI-----in fact, I would not want to waste money and shelf space on a display for the thing.

As already stated, you can make a server using any distro

The choice of the OS requires more than our say so. It requires you to have hardware supported, applications and services available.

For the most part the top 30 or so at distrowatch.com can be used as a server. There is not the great divide between a workstation and server as there used to be.

Most distros include all of the usual suspects when it comes to servers: Apache HTTP, Samba, NFS, not sure about mail, DHCP, SSH, etc. What kind of servers are you planning to run?
Almost none of the setup and administration is done with GUIs. Most people that are server admins don't need or want GUIs. It is easier, faster, and more straightforward to use a text editor and a commandline. What makes it easier is that instructions can be concise, such as 'run hortyflorty --xyz'. The respective instructions for using a GIU would go something like 'Find the GUI. Click this, then click that, then select menu-item blah-blah. Cross your fingers and click go'... When you see pictures of a large-ish server farm in rack-mounted computers, they mostly don't have consoles attached. Administration is done remotely with ssh logins.
Server processes tend to run with root privileges, and require root access to configure them. GUIs tend to be part of a desktop or window manager, which is not a recommended mode of operation for user root. Better to drop to root only when necessary, which is trivial from a shell commandline.

Yes, it does take a small amount of learning, but being a server admin requires that anyway. There aren't very many commands you would need to learn, over and above the usual collection of utilities and tools. So, your answer should probably be 'use any modern distro you already have'.

--- rod.

Guessing that you are looking for some form of file sharing services I'd suggest you look at Openfiler. Although most any distro provides these services this package is designed to be managed through a web interface.