Yeah, I was talking about Arch. Arch images aren’t available on a lot of web hosts, though.
Ubuntu Server isn’t bad. If you like ubuntu on your desktop, then you have the advantage of having a nearly identical environment on your server (minus Unity: win-win!).
CentOS rubs me the wrong way, but there’s nothing wrong with it, and it’s a very tried-and-true server platform. I’ll agree with Joe: if it’s already set up, and you’ve got no problems, just roll with it. If you have some occasion to start over and would like to try something else, go for it.