My answer in poster form. (SFW)
I *kinda *have a thing for red heads - but I can think of beautiful women in every category.
This. And I’ve gotta say that I prefer kind of a darker red–all other things equal.
Now, them orange redheads, well, not my fave.
All but a very few of the most important women of my life are/were brunette–mother, grandmothers, wife, girlfriends and one out of two sisters. (My mother’s father was a redhead and some aunts and one sister have/had red and/or reddish light brown hair.)
I voted blonde.
My first four girlfriends were blonde, including the little blonde girl that lived up the street when I was in 1st grade.
I guess I’ve been imprinted. Not that I’m griping…
I’ve heard second-hand about more people having called me sweet than a bitch, so…either I’m not hellspawn, or they’re way too scared of me to risk bad-mouthing getting back to me. 
As for the boys, I highly favor black/dark brown hair. Lighter shades of brown are not unappealing, though. And the occasional blond is interesting, but a fellow redhead is right out: a. people always ask if other redheads are related (not to mention my actual brother is a redhead) so, awkward! b. if I had kids with another redhead, all of our kids would most likely have red hair too, and being a lil redhead isn’t something I’d wish on kids I didn’t like, nevermind my own.
Just fine, baby. {Bats dark eyelashes}
In the interest of full disclosure, I used to be a very dark-brown-haired woman - the front has more grey than brown now. 
Well, I haven’t met you, and my sample size is likely to be statistically invalid. It could just be Mephistopheles sending his daughters to me, preying on my weakness, for his own fun.
Just because I’m paranoid doesn’t mean he isn’t really out to get me.
I voted “other”. Among the natural hair colors, I have no preference. For the past eight years I’ve been dating a brunette who was originally a blonde, but darkened over the course of our relationship. I like all of the natural hair colors, and hair is not the first thing that stands out to me when I look at a woman.
I do, however, have a thing for dyed redheads. I’m told that it’s strange because I’m almost a puritan in other respects; I strongly dislike tattoos and most piercings other than ear and nose (assuming the nose ring is a small stud). I’m usually anti-body mod in general; however, something about dyed red hair gets me. A quick perusal of Google images turned out the following charming fake-red ladies:
http://www.hellomagazine.com/imagenes//healthandbeauty/hair/201011034434/red/hot/hair/cheryl/cole/0-12-915/cheryl-hair--z.jpg
edit: this one is a bikini picture. SFW? http://images.tribe.net/tribe/upload/photo/663/2bb/6632bb42-6963-44dd-b67f-6475e9f17e40
Ok, I admit the last one didn’t come from a random Google search :D. Something about that fake red hue really does it for me though. Shame I don’t see it often IRL.
Creamy alabaster skin with freckles. Red hair top and bottom. 
Redheads all the way.
Can’t remember where I saw this, but it made me laugh:
You can sleep with a blonde,
You can sleep with a brunette,
But you’ll get no sleep with a redhead.
I’m a natural redhead…
Any are good.
Or none, with the right kind of face.
Very bright red or blond hair can be oddly cheery on a dark cloudy morning, but dark accessorizes better.
–
My particular weaknesses are for blue or purple. Maroon’s good, too. Green, I can take or leave.
My preference is a natural blonde. But I’ve never selected or rejected a woman only or primarily on the basis of hair color.
I have a fetish for dark hair (and eyes), the darker the better. I am a woman though.
Blondish boys are usually unappealing because of their coloring if nothing else, and red hair is a big turn-off.
This. Gingers all the way.
Brunettes for sure (I’m dating one - lucky me). Though there are also a few really hot blondes out there, and I had a definite thing for a cute redheaded girl in my Psych class two years ago. My hair colour preferences are pretty much the same for both genders, except I don’t recall ever fancying a redheaded boy. Sorry, redheaded boys.
Hello, YOU!
That’s ok too. I worked with a woman who had dark hair with grey mixed in and she was hot. I’ll assume the same goes for you.
Pics or it didn’t happen.
You’re very kind to an old lady. 