Honestly, from your description, I’d go with Debian, likely with btrfs. Would be better if you had 3 slots so that you can swap a bad drive but, 2 will work.
If you want to get adventurous, you can see about a Fedora Atomic distro.
Previously, I’ve recommended Proxmox but, not sure that I still can at the moment, if they haven’t fixed their kernel funkiness. Right now, I’m back to libvirt.