I'd go with ninjas as much as I <3 pirates, and while pirates did have guns, if you do some research you'll find ninjas actually also had guns, and even small portable cannons, they also had a mastery of the physical body, being able to completely manipulate their bodies to achieve the desired result. Cloak and dagger a true ninja used every part of his arsenal to make ends meet ( even his swords scabbard could be balanced on it's sword's tip and held in taught in the other hand with string to provide a probing device when searching a dark room for a hiding victim. The ninja would drop the string upon confirmed contact causing the blade to be exposed, where he would move in for the kill.) Ninjas by far are (in my opinion) far more resourceful and better trained. Most people think of ninjas as wearing black robes. Yet many ninjas infiltrated by dressing as beggars or wandering preists. All a ninja would have to do is dress as a pirate sneak on and poison the rum or plant a bomb in the bottom of the ship and steal a life boat, maybe set the gunpowder on fire on the bottom of the ship. Anyway Pirates, I luv ya but I'm sticking to ninjas.