Depends entirely on what you're planning to run! If it's just a basic Plex server or NAS, honestly a good B550 board like the MSI B550 Tomahawk will do you just fine with a Ryzen 5600. But if you're thinking virtualization with multiple VMs, you'll want something with more PCIe slots and better VRM cooling. The ASUS Pro WS X570-ACE is overkill for most people but gives you tons of expansion options.