The reality is that, today, ZFS is way better than btrfs in a number of areas, in very concrete ways that make using ZFS a joy and make using btrfs a pain, and make ZFS the only choice for many workloads. Even in single-disk laptop or desktop configurations, ZFS has a number of advantages over btrfs that will make your life much easier.
— How ZFS continues to be better than btrfs — Rudd-O.com in English
Very interesting comparison.
Keep one thing in mind when reading this: the author is comparing brtfs on Linux with ZFS on Linux, not ZFS on Solaris. ZFS on Linux trails ZFS on Solaris by quite some margin.