Gregory's ServerI'd go for btrfs because of the data integrity and flexibility at changing usage. Stick to RAID1 (c3/4 optional) or RAID10.
ZFS has integrity but less flexibility and isn't integrated with the kernel.
Ext4 is rock solid, but lacks the data integrity unless used with mdadm and dm-integrity, but could be too slow.
In any of the cases, a good backup is still vital.
(personally, I use btrfs RAID1 for years on #Debian and now #Devuan)