How low does the latency need to be? Express Router or Onprem Server?
Tiering ? ( Onprem Server then to Cool Storage or Netapp Files)
DFS?
Identity?
Security? Public Access not 2fa , use VPN
Throughput?
All Office Files been moved to Sharepoint?
Backup?
DR ( ZRS or LRS )

https://learn.microsoft.com/en-us/azure/storage/files/understand-performance