I think he meant "Pirates" because the option itself is capitalized, he just didn't use the " ".
I vote ninjas, because despite the fact that pirates have guns, you won't be able to see a ninja at night, and their weapons are noiseless so a whole pirate ship that is filled with drunken illiterate rapists can get owned by one ninja.
On the coolness factor, though, I'd have to side with pirates. They steal gold, rape women, pillage towns, and they are experts at boats and stuff which is badass because in their time the oceans were the frontier that seperated the known world from the unknown. Ninjas have to go through too much strict training and have to adhere to a code and such. No fun, just badass.