There is a great advantage to combining the filesystem with the disk mapper. You don't have to use different commands to add and grow disks and the partitions

There is a great advantage to combining the filesystem with the disk mapper. You don't have to use different commands to add and grow disks and the partitions upon those disks. Your filesystem knows about what it's living on and stores data accordingly. ZFS has more advanced file system properties, like sending snapshots, even of block devices. BTRFS is still working on feature parity with this. ZFS is much more stable than other FS with similar features. The big disadvantage is the memory and CPU requirement. If your server has plenty of memory and CPU, I'd use ZFS. If you're running on an ARM NAS with 128MB RAM, I'd use something less fancy.