Trying to decide what OS to use on my new NAS for purely shared storage

[Davvo]

@Serf

Then the 12 6tb drives as singe pool I guess it would be called. With 1 or 2 of the drives being parity like would be for raid 5/6. The pool would be one large share that any VMs could mount folders from, read/write to as storage but not where the OS’s reside. ON my main PC I could mount it as a network drive for instance.

Then I suggest either two RAIDZ2 VDEVs or four three-way mirrors.
I also suggest reading iX's ZFS Pool Layout White Paper.