Debian or Ubuntu

I'd say to use Ubuntu, since you are already familiar with it. They're not that different, so go with what you know.

Ubuntu is more popular than Debian at Linode anyway.

Ubuntu LTS (10.04) and Debian Stable (6.0) are more or less on par in every respect, including security and stability. It's just a matter of preference. Debian 6.0 currently has slightly newer packages because it was frozen a few months later, but this shouldn't really matter, either. In any case, if you need packages that are newer than the ones in the official repositories, Ubuntu has PPAs and Debian has dotdeb and backports.

There's the argument that Ubuntu is easier to use than Debian, but I don't see much difference in that department, either. Most of the things that make Ubuntu easier to use are geared towards desktop users. If it's a server and all you have is an SSH shell, the difference is minimal. The only thing that I can think of off the top of my head is Ubuntu's "service start/stop/restart" command, and the only reason this exists is because Canonical wants to steal customers from Red Hat.

Long-term support is slightly different. Ubuntu 10.04 LTS Server Edition is supported until April 2015, whereas Debian Stable is supported until one year after the release of the next stable version. Debian 7.0 is expected to arrive in early 2013, so if you stick with Debian 6.0, support will end in early 2014. Take this into consideration if you don't want to upgrade for a long time.

As hybinet said, for a server build from standard packages, it makes little difference – go with what you are used to or the one where the long-term support best matches your requirements.

If you will want to use more up-to-date software than is included in the standard distros, it comes down to whether you prefer getting it the Ubuntu way or the Debian way. I have a personal preference for Debian, because backports and dotdeb seem more 'organised' and I have run into problems a couple of times using PPAs -- but maybe that's just me.

I personally go for Ubuntu due to the fixed LTS release schedule.

Thank you guys for feedback. I think I'll go for ubuntu too and I'll clone the system (sw) on my local server in order to publish only when I know that everything it's working fine :)

Advantages of Debian:

1. Security support for 100% of archive.

In Ubuntu only the packages in main are suitable for use on a server because everything else has zero security support for the duration of the lifetime of the LTS release. That's a long time. This severely limits your package choices on Ubuntu.

2. Ease of upgrade. Upgrading from one LTS release to the next isn't nearly as easy as upgrading from one Debian stable release to another. I have one VPS at another provider that's been going since Sarge (3.1) without a reinstall but upgrading through Etch, Lenny, and Squeeze without a reinstall. The only problem I've ever had is with moinmoin. My wikifarm isn't auto-updated on upgrade and has to be updated manually.

Debian is more advantageous than Ubuntu.Debian is focused on stability with infrequent releases. It is not intended to make sensible defaults. It makes the user understand what's being installed or installs a "default" desktop, which usually has a lot more applications than you need.If stability is what you want, you want Debian. If you can handle a little instability and want frequent releases and an "easy" installation, Ubuntu is for you.

Ubuntu is more advantageous than Debian. Ubuntu is focused on stability with predictable releases. It is not intended to make unpredictable defaults. It makes the user understand what's being installed and doesn't installs a "free" desktop, which usually has a lot of applications chosen for ideology rather than functionality. If stability is what you want, you want Ubuntu. If you can handle a little unpredictability and want random releases and an "easy" installation, Debian is for you.

See what I did there? I don't really have a problem with Debian (other than the ideology part), but the intention is to demonstrate that these sort of arguments can be made in pretty much any direction against any distro. They all have their strengths and weaknesses, and the decision should be made based on what's going to work best for you. For many people, the ability to get help and documentation from the community is important, so that's something to ensure is available when choosing a distribution. Making sure that the distro has the packages you want/need, or an easy way to get them, is also important. Making sure that it's compatible with your administration style is important. Making sure that the release schedule is compatible with what you want to do is important. For example, a distribution with bleeding-edge rolling updates might be better suited for a development environment, while a distribution with fixed updates and frequent backported fixes might be better suited for a production environment. There's all sorts of scenarios that are better suited to different styles.