In $dayjob, I'd still go for gluster over ceph, with zfs on my storage nodes -- this obviously depends on what you're doing but in my case this would be shared storage for everything from images, logs and dataflow between some chunky legacy apps.
Why this stack? For no other reason really other than it works perfectly, has caused me almost no pain in the 6+ years I've used it for this kind of DFS stuff (across several clients) and there are no features I need in ceph which would make me take the less mature option.
I've been using LeoFS a little lately also again ontop of ZFS and it's working reasonably well (S3 compat stuff).
Currently why anyone would use HAMMER2 or BTRFS for anything important escapes me.
