The missing museum history of minor warships

Which minor warship classes from the Second World War most deserve museum preservation?

German R-boats and small Italian destroyers are suggested, within a much wider shortage of preserved destroyers and small craft.

German R-boats and small Italian destroyers are personal choices for museum preservation. R-boats did substantial work but attract less attention than E-boats. Hundreds of destroyers and thousands of smaller vessels served in the Second World War, yet very few survive. Their collective work deserves representation alongside larger warships.