Your right about btrfs and raid, but there are other aspects that spook me about it, CVE-2019-19377 being the last recent big scare which actually caused me trouble this week (was finally patched on a particular kernel this week).
Linus’ issue with ZFS was years and years of negligence. Cutting corners is one thing, ignoring the health of your data for 4-5 years does not make this a problem with ZFS. Add hardware failure to that (the backplane) and it should have been more disastrous than it was.
You really only need to watch the first 5 mins of this video to understand that any explanation you got from Linus as to how ZFS works should be discarded. (Though watching the whole thing will help you understand that if they weren’t using ZFS, recovery would likely have been impossible).
As for the thread poll, I use BTRFS on desktop (openSUSE Tumbleweed) and ZFS on servers. The BTRFS snapshots have saved me time more than once when playing around with desktop distros.
Ext4 is the most mature. You can do things like shrink an Ext4 partition (with gparted) if needed, while most other file systems only support growing. Ext4’s performance is also very good. Does not support transparent compression, deduplication or snapshots.
XFS is pretty mature and performs well. In recent years XFS got batch/offline deduplication (with reflink) and more reliable file system repair/recovery. No compression or snapshots.
ZFS is mature and has advanced features like RAID, ARC, snapshots, encryption, transparent compression and live deduplication (but dedupe destroys performance),
BTRFS is getting mature and implementing more features, but lags behind ZFS. Only useful (over ZFS) if deduplication is needed without the performance hit (batch/offline with reflink like XFS).
I use lvm+btrfs for / root, lvm+ext4 for logs/cache/temporary files in /var, /tmp, and cephfs for user home directories under /home, media library, or other project based folders.
Media server, ext4 on SSD as a cache (lots of large random mmaped read write - anti pattern for cow), btrfs on a pair of large spinny (one fs per disk, metadata dup, space_cache_v2), MergerFS on top of it all for media players, scripts move data cache->spinny.
XFS is the best for desktop use the performance is very cool , also try it on the new Ubuntu release from daily builds for some reason applications are launching fast as hell ! I don’t know what improvements it has in that version but performance in general seems much improved !
If you like to edit videos for example thats another reason to use XFS because its the best for handling big files !
Take the decision and switch to XFS now !