Verificou a documentação de ajuda dos dois cmdlets.
O Set-WSManQuickConfig realiza o seguinte:
-- Checks whether the WinRM service is running. If the WinRM service is not running, the service is started.
-- Sets the WinRM service startup type to automatic.
-- Creates a listener to accept requests on any IP address. By default, the transport is HTTP.
-- Enables a firewall exception for WinRM traffic .
Enable-PSRemoting também faz o que precede e, adicionalmente:
----- Registers the Microsoft.PowerShell and Microsoft.PowerShell.Workflow session configurations, if it they are not already registered.
----- Registers the Microsoft.PowerShell32 session configuration on 64-bit computers, if it is not already registered.
----- Enables all session configurations.
----- Changes the security descriptor of all session configurations to allow remote access.
----- Restarts the WinRM service to make the preceding changes effective.
Portanto, Enable-PSRemoting
é o único a ser usado, a menos que você pretenda configurar sessões manualmente.