The chayote plant seems to be the most versatile of the three, with the tubers being consumable as a starch, the stems and leaves edible as salad fiber. The blue potato plant was mentioned only in terms of its bluish, flattened tubrous roots, used as traditional potatoes are used, in baking, frying, and salads. The Jerusalem artichoke is not really descended from Jerusalem, being discovered by Native
Americans for years before the European settlers got here. The Jerusalem artichoke is known for its ginger-like tubers, in addition to its strong resemblance to the garden-variety of Helianas sunflower. It produces flowering heads, ripe with seeds, so you get the best of both worlds here, between seed production and tubers. If I had to arrange them in terms of versatility, I would place the chayote plant numero uno, the Jerusalem artichoke in second place, and the blue potato in third place.