""the btrfs file system;" - Pretty reasonable, zfs is much better
ZFS is much more complex than BTRFS, its memory-intensive, and still lacks capacity expansion (RAIDz expansion was just announced to become available somewhere next year while outside ZFS capacity expansion functionality has been commonplace for decades). And while ZFS is pretty robust, if things go wrong then there isn't much a user can do to recover aside from rebuilding the storage setup and restoring from the last good backup (which hopefully exists).
BTRFS on the other side is equally reliable (just stay away from it's built-in RAID5/6 functionality and use dmraid or hw RAID instead), less resource hungry (and performs better on systems with limited resources), there are tools to repair file system damage and it has had basic features like capacity expansion for ages. The fact that it's been the default (and fully supported) file system for SUSE Enterprise Linux for several years now just shows that BTRFS today is nothing like it was 10 years ago.
ZFS is great for a storage system which doesn't have hardware RAID, but for a desktop system it's overkill.
Biting the hand that feeds IT
