Most of my collection is men singing, but I think that women are generally better singers than men. However, I just don’t really listen to the styles of music that women predominantly sing for… Mostly just heavy metal where mens voices rule, and country drinking songs.
The clear majority of my music collection and favorite CDs have male singers. I don’t think this is because I prefer male voices to female voices, so much as other factors:
There are a lot more male singers and male-fronted bands than females, at least in the styles and types of music I prefer (for every Bangles or Go-gos there are dozens of male melodic rock bands); and
Male singers tend to sing songs written from the male point of view, which I can more easily identify with, and in my experience are more likely to sing about more interesting and eclectic subject matter (is there a female equivalent to They Might Be Giants?).
My first knee-jerk response was “male” because when I think of singer my first thought is Frank Sinatra and that’s because the first voice I know I heard singing was his – in the 1940’s! Frank was my template for singing. But later, voices like Rosemary Clooney and Ella Fitzgerald broadened (no pun meant) my tastes to the point that any singer with a good set of pipes and clear enunciation was pleasant to listen to.
I must say that I prefer instrumental music, primarily jazz, and for the longest time I didn’t buy any vocals. In my 30’s or later I let down on that restriction but a guess (without going to do an actual count) is that my collection is mostly male.
An additional comment about vocal preferences is that I have always been drawn to “unique” voices like Richie Havens, Blossom Dearie, Tom Waits, Teresa Brewer, and so on. But I rarely buy their records. Gregg Allman is the only exception I can think of right off.
If I had to name my favorite active singer these days, it would be Kenny Rankin.
I like both. I sort of prefer a manly gravelly male voice like the singer of Social Distortion or Godsmack, or a banshee scream like Robert Plant. I don’t like whiny long and drawn-out vocals, like Radiohead or Muse tend to do. I love Radiohead and Muse though.
For females I’m a sucker for a sweet voice like Lily Allen and Kim Deal, or a rocker like Joan Jett or the singer of Babes in Toyland.
It’s all good.
Thought of another factor: I do tend to prefer vocalists who have a wide range and can adopt a variety of vocal personas and styles (like, for example, David Bowie or Paul McCartney); and males seem to have more versatile voices than females.
My favorite singers seem to be split pretty equally by gender.
Nina Simone, Poly Styrene, Tanya Donelly, PJ Harvey, Neko Case, Chan Marshall
vs
Tim Buckley, Alex Chilton, Tom Waits, Frank Black, Stuart Staples, Nick Cave
The only pattern I notice is that I tend to prefer deep voices with a few exceptions.
My mp3 player is almost overwhelmingly female-singer-oriented, and I think it is for the same reasons you mention here. My favourites are Bjork, Sarah Brightman, Natalie Imbruglia, Kate Bush, The Cardigans, and Lisa Ekdahl, and I also tend to like music in the teen-pop genre (Cheyenne Kimball, Aly & AJ, Avril Lavigne, Lillix, etc.)
I’m with ya here. Garbage, the Sounds, Veruca Salt, theSTART, No Doubt, Tigers & Monkeys…
I definitely tend to prefer men’s voices, even though I’m a soprano who makes CDs of songs to sing along with in the car. 
When it comes to choral music I’m all about male voices: I love men’s choirs, barbershop, etc. And I’d usually rather sing/harmonize with a man than with another woman.
I do own some female music, though: Melissa Etheridge, Indigo Girls, Madonna, Annie Lennox, Sweet and Lovely: Capitol’s Great Ladies of Song Vol 1, etc. There are current female artists who I like but don’t have albums by, like Pink and Avril Lavigne (and, I’ll admit, Katy Perry), but the only female artist in my car right now is Sara Bareilles: I’ve been obsessed with her album Little Voice for several months.
Agreed.
No preference.
I had a friend who interned with a fairly large rock station and the old ‘don’t play two female vocalists in a row’ rule was up and running (though this was about a decade ago).
Definitely female. I like most of the really big name male singing superstars - Elvis, the Beach Boys, Bruce Springsteen, Billy Joel, Bon Jovi to name a few - but for females, I like most of them, even those of lesser reknown and/or talent.
I prefer androgynous male vocals. The higher-pitched, the better, mostly.
My initial impulse was to say “no preference.” But then I checked my collection, and there’s a strong female-artist bias.
More female than male. I have broad musical tastes, so I’ve got a decent mix of stuff, but I think there are more female vocalists overall. I tease a friend who has almost entirely male vocalists in his collection that he’s secretly gay. He’d rather be surrounded by men than women. I, on the other hand, like the sound of estrogen in voices. 
Almost all of the music I listen to is by males. I’d say about 80-90 percent of it.
Oh and I realize this thread is almost a month old. I can’t believe I missed it the first time around.