I believe I can safely say this is the definitive list of the eight ships any serious player of Pirates absolutely must include in their collection just simply because of their low cost and incredible usefulness. A good number of these ships will never leave their HI's, as they are ideal for carrying 0LR fleet builders and other valuable crew who are best served remaining out of the fight. The others are the all-out treasure runners whose only purpose is to get to the WI's first, setting up trade currents along the way for the rest of the fleet. In either role, these ships are also ideal for players who like to use the lesser factions in mixed fleets, in order to gain all the benefits of the big factions' better crew.
I feel their can be but little argument as to most of them, all the same, you can be sure of one thing: if you don't have these pieces, your opponent will.
(Spain's El Raton narrowly missed making the list - I don't know about anyone else, but mine moves S+L? )