LOL, as a guy with 6 older sisters.. listening to them growing up... I would say men ;-)

just an observation from a male perspective. women tend to be more in touch with their emotions, and they carry them closer to the surface.
so they cry when their happy, they cry when their sad, they cry when their hurt.

but when a man cries.. it's basically when he's lost something/some one that he cant handle loosing. something that hurts so deep, that the tears are forced out of him.
but, thats just my thoughts.