ZFS or BTRFS as the best way to setup a dedicated urbackup server?

OP here
So, just yesterday I put arch linux on a usb stick from which the system boots
and the two 500GB drives are mounted just for pure backup storage, btrfs raid0
mounted in fstab with these flags:
defaults,compress=zstd,noatime,autodefrag,subvol=@

will be running this setup and see how it goes and behaves.