I don't... understand the question. "Prefer it for male or female"? I'm a male, I like it. I know many females who like it. Where does the preference come in? Or are you referring to male or female characters, and if so, what are you asking us to prefer about them?
I prefer it because of the guys!!
There are only a couple of female characters that i actually like or rather i think are not weak. (i DO like most of em) To me most of the female characters are not presented as strongly as the male, but then again it is shonen an is meant to be an action/adventure type which to me would mean more of a guy oriented series. ya know...tough guys,cool fights, etc etc... ;)
I like it for both. I prefer it for the males in it (a lil bit more- bias because so many are sooo HOT...and I have two MAJOR crushes there and a couple minors...) but there are many females too that have very interesting characters. I like it for their personalities.
I notice this manga title is labeled Shonen Jump for guys. But it's a fair game to have guys and gals like this kind of anime if they are interested in liking the series. In my case, I watch a mixture of episodes although I don't have time to catch up the whole series. At least the flashbacks would help me remember on what happened in the past scenes and sagas/arcs.