I'm not sure about the "and vice versa" part because I've been lately seeing here a lot of "I want to practice English, women only" language partner requests from females. And many women say that they only want girl partners in their student introduction. Where, if I may ask, did you get the idea that women prefer male language partners from? I'm just curious.

As for my preference, my language partner's sex absolutely doesn't matter to me. I may prefer partners that are closer to my age, with the same beliefs/hobbies, with a particular accent, from a particular country, but I don't care if this partner is male or female. It really doesn't make any difference. I just like learning languages by speaking to people.

In my opinion it depends of individual preferention. 

I prefer men, because they are more simpletone and focus on the most important thing, like spelling, accent or actually topic. They talk about one topic in one time. But of course, if some woman want to talk with me, I will do it with my pleasure. I do not categorised, I say about it because of my experiences.

I am a woman and I know, that we could talk f.e. about weather and think about dinner :P