Stephen Foskett has written a detailed post about why he considers ZFS the Best Filesystem (For Now…) [fosketts.net]. He starts out:
ZFS should have been great, but I kind of hate it: ZFS seems to be trapped in the past, before it was sidelined it as the cool storage project of choice; it’s inflexible; it lacks modern flash integration; and it’s not directly supported by most operating systems. But I put all my valuable data on ZFS because it simply offers the best level of data protection in a small office/home office (SOHO) environment. Here’s why.
It's been a long road to get to where it is and there have been many hinders, including software patents and malicious licensing.