Btrfs came default with my new Synology, where I have it in Synology's raid config (similar to raid 1 I think) and I haven't had any problems.

I don't recommend the btrfs drivers for windows 10. I had a drive using this and it would often become unreachable under load, but this is more a Windows problem than a problem with btrfs

What kind of disks, and how is your ZFS set up? Something seems amis here.

Did you set the correct block size for your disk? Especially modern SSDs like to pretend they have 512B sectors for some compatibility reason, while the hardware can only do 4k sectors. Make sure to set ashift=12.

Proxmox also uses a very small volblocksize by default. This mostly applies to RAIDz, but try using a higher value like 64k. (Default on Proxmox is 8k or 16k on newer versions)

https://discourse.practicalzfs.com/t/psa-raidz2-proxmox-efficiency-performance/1694

Don't use btrfs if you need RAID 5 or 6.

The RAID56 feature provides striping and parity over several devices, same as the traditional RAID5/6. There are some implementation and design deficiencies that make it unreliable for some corner cases and the feature should not be used in production, only for evaluation or testing. The power failure safety for metadata with RAID56 is not 100%.

https://btrfs.readthedocs.io/en/latest/btrfs-man5.html#raid56-status-and-recommended-practices

You shouldn't have abysmal performance with ZFS. Something must be up.

My setup is different to yours but not totally different. I run ESXi 8, and I started to use BTRFS on some of my VM's.

I had a power failure, that was longer than the UPS could handle. Most of the system shutdown safely, a few VM's did not. All of the EXT4 VM's were easily recovered (including another one that was XFS). TWO of the BTRFS systems crashed into a non recoverable state.

Nothing I could do to fix them, they were just toast. I had no choice but to recover using backups. This made me highly aware that BTRFS is still not a reliable FS.

I am migrating everything from BTRFS to something more stable and reliable like EXT4. It's simply not worth the headache.

A bit of topic; am I the only one that pronounces it "butterface"?

No reason not to. Old reputations die hard, but it's been many many years since I've had an issue.

I like also that btrfs is a lot more flexible than ZFS which is pretty strict about the size and number of disks, whereas you can upgrade a btrfs array ad hoc.

I'll add to avoid RAID5/6 as that is still not considered safe, but you mentioned RAID1 which has no issues.

I am using btrfs on raid1 for a few years now and no major issue.

It's a bit annoying that a system with a degraded raid doesn't boot up without manual intervention though.

Also, not sure why but I recently broke a system installation on btrfs by taking out the drive and accessing it (and writing to it) from another PC via an USB adapter. But I guess that is not a common scenario.