Well my main server is currently at 16 drives plus 2 SSDs, so 18 total counted for the licence, arranged as 12 drive unraid array and 4 drive ZFS, plus an appdata+vm disk and a general cache disk.
I’d like to go with Ceph eventually, because I think it’s a solid platform, but multiple nodes and a heavier duty network backbone would be required to do that properly, also the extra disks required to protect a ZFS array of multiple Vdevs, which is safer and faster sure, but the costs are significantly higher than just buying an unraid licence.