Three missing types of nonmilitary museum ship

Which three nonmilitary ships from history would make the most valuable museum ships?

Representative East Indiaman, great liner, and tramp-steamer types would each preserve a major form of trade or travel that has largely disappeared.

The preferred museum ships are a large East Indiaman, an Olympic- or Britannic-era liner, and a tramp steamer rather than three famous names. Together they would preserve the working ships behind imperial commerce, mass passenger travel, and the ordinary movement of world trade, subjects poorly represented by surviving museum fleets.