Man hair!

[Anthy]

I think it really depends on the setting for what's appropriate, but I personally like medium-length to longer hair. I agree with Aleema, the high ponytails or topknot/tied-back look is awesome (I like them on both male and female characters, it's an all-around good look).

By the topic definition though I would really dislike short hair D: Buzz cuts or crew cuts make me die inside... not to mention I associate it with my guy friends who are like "hurrrr well it's easy to take care of" but then flip a bitch when I get a shoulder-length haircut. Or if it's like super neat always freshly-trimmed-looking short hair, it trips homicidal sociopath flags >___> Some short hairstyles are okay, as long as they can pass the barrette test (ie. if it's long enough to arbitrarily cover in hairclips, it's acceptable). I prefer more "overgrown" shorter hair, especially if it's wavy... though I love straight hair more for long styles

But if it's a "realistic" school setting and this guy has long long beautiful hair, it's going to look really off to me. Especially if no one finds it unusual. Even if it's pretty, it's off. (though I still might pursue them anyway)

[sake-bento]

ME LIKE TOPIC. HAIR GOOD.

I like ponytails in general, but I have a HUGE lady boner for high ponytails (top of the head). Most commonly seen in ancient Chinese and Japanese hairstyles, but for some reason, they drive me wild:

Thiiiiiiiiiiiiiiiiiiiiiiiiiiiiis. In fact, have a picture of my boyfriend as proof of my love.

Typically, I prefer longer hair on slimmer boys, and shorter hair on the larger ones. Messy bangs always do it for me, too.

[Aleema]

Thiiiiiiiiiiiiiiiiiiiiiiiiiiiiis. In fact, have a picture of my boyfriend as proof of my love.

So a modern guy can pull it off!

[Auro-Cyanide]

I do have a thing for pony tails (low) but I have liked all kinds of hairstyles. It depends what type of man is wearing it. What I think is most important is that a) the haircut they have suits them and b) they keep it nice. While I have a thing for ponytails, a lot of the time I see them they are very unkempt and I dislike it. I keep very far away from guys who don't have certain pride in their appearance. It tells me a lot about how the take care of things :/

[Deji]

Ponytails (super shport one, medium length ones, long ones... ALL OF THEM *_*) are a weakness of mine. Well kept long-ish hair is appreciated as well.
I don't really like short hair =/ And super short hair just a few millimeters long to shaved hair... that is a complete turnoff.

My first boyfriend had a lovely jaw-length golden curly hair that I died for, but he refused to keep it longer and get a ponytail... until after a couple of years after we broke up. I was so mad at him! XD;
My second boyfriend had a shoulder-length ponytail when I met him, and it grew to chest-length braid while we were together. I loved it, though it was really greasy when you got to actually touch it due a condition he had, sadly >:
My current boyfriend, who completely hates his hair, kept a ponytail for several years just I because I liked it ^__^
... then he cut it super short because he couldn't stand it anymore xD; Now I keep my hair long instead in return ^^

[natsumachi]

Um, seconding the old-school Japanese/Chinese high ponytail styles. I especially find this appealing on suave older men.
On younger guys I prefer short-medium length, with a messy/curly but styled quality.

But I think as long as it looks well-cared-for and stylish any length can be nice.

[Joey]

Medium length/short hair! I think shorter haircuts accentuate manliness, which I think is pretty charismatic. ^^

I'm surprised that so many people don't like guys with shorter hair :< In the Asian entertainment scene most boy bands/solo singers/actors seem to be moving from long hair to shorter haircuts, so from what I can see it seems to be the "trend" now. But I guess longer hair lends a more fantasy-ish/bishonen appeal, which I can understand XD

[Endorphin]

Joey, that depends. =o
For example, the lenght of the hair of your avatar - that's something I consider sexy too.
But I don't like it when the hair's so short that I can't even grab it or something. >_<"

But you're right, long hair really seem popular. xD
(I prefere low, ultrashort ponytails, but it's all kinda cute.)
But this means more short haired guys for us! ;D /fail

[MiSi]

I think, I especially like pale (blond, white or silver) hair. Even more, when it's extremely long... (but I guess, the length doesn't really matter. For example i ended up liking one of my sister's OCs, who is an ex-soldier and therefore really has extremely short hair, just because he looks so damn charismatic, that badass )

But I also go for guys with dark (blue, black, ...) hair, in combination with some hot glasses

[Omnificent]

Shag or mop length is the best. No crew cuts, no emo-hair, no dudes with hairstyles clearly grafted from the head of a 12-year-old girl, ponytail length hair only if you are a metalhead/Viking/samurai/womanizer/can otherwise pull it off.

But really it depends on the character design/style. Go with what makes sense.

[kingjing]

Bi dude reporting.
Surely you're designing more than one guy. Variety is the spice of life! (the lack of bald guys in bishi games saddens me)
Personally, I like shorter hair, but I really enjoy seeing different styles. I like to have my aesthetic sense challenged.
Though I guess that's not really the best way to make popular designs... ^^;

[Gear]

These certainly were not the responses I was expecting, though I might have if I'd taken into account the specific variation of individuals I was addressing. The responses have been very enlightening. I've been having difficulty giving one of my characters longer hair despite my efforts, but it would appear that it would be in my best interest to keep trying.

[sake-bento]

These certainly were not the responses I was expecting, though I might have if I'd taken into account the specific variation of individuals I was addressing. The responses have been very enlightening. I've been having difficulty giving one of my characters longer hair despite my efforts, but it would appear that it would be in my best interest to keep trying.

If it doesn't look right on him, it doesn't. Not everyone has the right "look" for long hair, and there are lots of guys with short hair who can still be immensely appealing.

[Dollywitch]

I find short hair the least attractive but it depends on the character really.

I think I prefer bald to short hair nearly.

[Gear]

@sake-bento: The problem is, I personally don't like long hair on ANY guy. So I can't trust my own opinion on the matter.