Funny that this should be brought up - I was thinking about it the other day whilst devising a character for an RPG. (I shall stick solely in RPG terms for now).
I don't really consider myself to prefer either gender - I'm fairly relaxed to either one. But recently, I've ended up veering to male characters, pretty much completely! The last female I played was in 'Escape from Nurn' in the Shire, and much have been...well, it actually ended a good few months ago, anyway. But all the characters I'm playing at the moment and for the past few games have all been male.
Possibly this is because I originally ended up with a bit of a stigma with one of the moderators (you know who you are!) that I always played female elves or people with magical powers
I know, I know... so my first non-female character was somewhat experimental, after playing all my first games with female characters, and was the Easterling character Kane in 'Ride To The Dark Side'. (I don't include the hobbit character I played - he was a rather mischievous child and almost genderless!)
Incidentally, I found he was quite marvellous to play! Things which were much trickier to execute as a female characters were made simpler by playing a male - not really physical things, as my characters were never weak: they weren't Mary-Sues (honest!!!), but they were hardly weak. Believable though, and with a tendency to die... But also, it seemed easier to make Kane more introvert - by playing more on his feelings, for example in his relationship with one of the female characters (Rhana, played by Maikadilwen), I was able to make him a more unusual character. Strange, because it would be
expected to exaggerate them more with a female character, but with a male it made him different. And since then I've played
way more male characters, actually....
However, this is
not a preference - it's simply what seems more practical at the time, for the specific RPG.
My characters do end up with some of my traits though, quite often - sense of humour, a slightly cynical outlook and, yes, green eyes, are quite often included in their bios
I suppose this is just because I like to put a part of myself into my characters - and this is my way of doing it.