ZFS on Linux is where the majority of ZFS innovation is these days. Btrfs should be permanently deleted except for a sole copy in a museum somewhere as an example of a historical mistake negatively affecting millions of people.
Might be unfair, but I've learned my lesson there. I decided to follow the spectactle from a large distance.
Perhaps it's a vocal minority, but does it matter? Isn't the error rate what's most important? I've seen ZFS horror stories too, but not nearly as many, and that says something at least.
Disclaimer: I've never used btrfs. I quite like ZFS.