Synology DS1815+
I've spent hundreds on a free standing 22u rack mount cabinet, 12 bay chasis, ECC RAM etc for a ZFS file server project which a year on still hasn't gotten anywhere. The file system while great, just wasn't suited to me with outlaying thousands of pounds on drives in one go to maximize space efficiency. Also, I just don't need it. I spend enough time around network cabinets and server issues in work. I want something that just works!
I've been keeping an eye on Synology, there hardware is expensive and yes you could build you're own for much cheaper but I wanted a plug and go system.
Recently their new DSM 6 (beta) OS now supports BTRFS on particular models, this was what made me jump on it and order one. Purely for the error detection and correction inherit of the file system, quite similar to ZFS.
I plan to load the bays with 3TB drives over time, with SHR-2 (RAID6 equivalent) will give me 18TB usable storage.