Dangerous territory with this question so please try to be impartial and instead focus on what to look for when choosing a Linux distribution.

I'm completely new to Linux. I thought it'd never happen but I need to have a Linux box to play with and I have a spare fanless Atom PC (32-bit only).

I'll be using the machine as a non-commercial hobby server, the trouble is, I don't even know how to compare Linux distributions and why people pick one over another.

If anything, I want to have an easy install from USB stick.

My question is: what do you look for when choosing a (free?) Linux distribution for a server?

If you can, please explain what sorts of things actually differ between one and another without saying which you think is better, just the facts.

The way I see it, Linux as a server is just an SSH console and I find it hard to imagine what could be different between one and another.