Having implemented or at least rewritten most storage backends in LXC as well as LXD has left me under the impression that most storage tools suck. Most advanced storage drivers provide a set of tools that allow userspace to administer storage without having to link against an external library. This is a huge advantage if one wants to keep the amount of external dependencies to a minimum. This is a policy to which LXC and LXD always try to adhere. One of the most crucial features such tools should provide is the ability to retrieve each property for each storage entity they allow to administer in a predictable and machine-readable way. As far as I can tell, only the ZFS and LVM tools allow one to do this. For example
zfs get -H -p -o "value" <key> <storage-entity>
will let you retrieve (nearly) all properties. The RBD and BTRFS tools lack this ability which makes them inconvenient to use at times.