this is an age old question. which is cooler: ninjas or pirates? recently there has been a strong upturn in people who would claim that pirates are cooler, but i think this may just reflect the current rise in popularity due to the film pirates of the caribbean. in my opinion the obvious choice is ninjas.
sure, the life of a pirate has some great elements: a life of no responsibility, the promise of adventure, cool pets like talking birds and monkeys, tons of treasure hunting and the like, and an excuse to say "arrrrr" anytime you want. but the downside vastly outweights these positives: most pirates have a limb or two missing, they are often betrayed by their best friends, can get really sea sick, and dont even get me started on the scurvy...
ninjas on the other hand have a lot going for them as well, such as: cool costumes, tons of weapons like throwing stars and katana blades, the ability to lurk around in the shadows unseen, and a strong sense of honor among peers. even with all that great suff, there is still a downside: that whole honor thing also means you might be killed by the brother of someone you kill (or vice versa), and it is a fairly solitary life.
but i think all in all, the life of a ninja is totally cooler.