Well, it comes to what your knowledge is. Have you ever managed a VPS or dedicated server before? and are you comfortable? If not then a managed option is best as the provider will handle all technical aspects of the server.
Managed- Provider will secure, update, optimized, install server software, and handle any request in regards configuration changes you might require.
Unmanaged - End user is responsible of getting the server up and running securely and ensuring software is properly installed and configured.