If I had to pick one, Arch. I already use it a lot, so it's familiar. I know my way around the package manager and how to create packages, so even when things aren't available for Arch out of the box, I can make it work.

It'd be kind of a hassle trying to keep anywhere close to 100% server uptime, but for my own personal stuff that shouldn't be that big of an issue, as I can fix it when I have the time.

For desktop, I basically can't do stable release. I frequently mess with new projects requiring the latest versions of everything, which is a near impossible task on stable-release distros.