Girls. While there are plenty of stupid answers from them, for the most part they answer honestly. For the guys, there are a lot of misogynists and a lot of perverts (the creepy kind, not the fun kind), to the point that I sometimes don't even bother reading male responses.
Normally both unless it is a question about what women want in a guy. Most girls aren't honest with themselves, and always go for a politically correct answer, instead of saying something that will make them sound as shallow as a guy might say. Instead we get answers about them wanting a sweet guy, that we all know is the kind of guy destined for the friend zone. In all other matters I take the advise from guys and girls equally.
For relationships, I seek more of an "older" female opinion. 25+
For politics, since majority here are bandwagon or undereducated liberals I look toward a libertarian/conservative viewpoint from either gender.
It really depends on the topic. In some cases I value women's answers more and in other cases I value men's answers more. That being said, there are users of both sexes that give well reasoned, thought out, and honest responses that I appreciate.
If I'm asking a question here, it's because I'm interested in getting to know people's opinions on it and therefore I usually don't care if they're male or female. It's true many people (both genders) just give short and general biased replies, but I try to filter over those and learn by hearing from different points of view/ experiences.
Then it also depends on the sort of question, to whom are they directed to...