Boat Engine Outboard Motor 4 Stroke buyers years back were created rightfully leery of ship packages when some dealers priced them with puny outboards, then coached the customer up to a more respectable power plant before closing the deal. Those who spent the extra dollars for a bigger motor proved generally well-served; people who remained with a little 5hp Outboard Motor for the reduced cost point were often frustrated.
Things are better now: There are fewer underpowered packages on the market. However, larger is usually better.
Among the worst things you can do would be under-power a ship. You'll never savor the functionality built into the hull. You won't be as prepared to scoot from an approaching storm.
Going using the ship manufacturer's maximum score, found on the inspection plate, is a fairly safe bet. If you're on the fence, you can check with boat manufacturers, who normally have available evaluation data on the ship of your choice powered with assorted makes and models of engines.