How to choose: answering the main questions
Storage system or storage server: what is the difference?
Branded storage is a turnkey solution with vendor support and proprietary drive pricing. A storage server is a standard server platform with a high-capacity chassis and open-source software like TrueNAS or Ceph. For 90% of SMB tasks, the latter is more cost-effective and flexible.
What kind of network is needed for storage?
Minimum 10GbE for file access and virtualization; 25GbE if the storage serves datastores to multiple hypervisors. Onboard 1GbE is sufficient only for archives.
ZFS, Ceph, or hardware RAID?
ZFS (TrueNAS) is the best choice for single-node storage: integrity control, snapshots, and compression. Ceph is for when you need a cluster of 3+ nodes. Hardware RAID remains for Windows scenarios and simplicity.