Personally, I'm about 15 years ago since I jumped into this culture. Am I to come between state that women are the better singers. It may also be because the anime, games and outside of the two, is sung mostly by women. (...) Of men singing anime and games are kinda weird, but in women it is different: For it sounds nice at first, and epic: for example, the songs of the group Kalafina (made up with KnK of Fate / Zero projects), I almost had to cry when the tears. The opeing song [Answer] by Rekka Katakiri in G SnM. other hand, is a real Groovy song. ...
Based on your information, you still have more to grow and to learn about music, artists, the entertainment industry, and other factors that pertain to the topic.
Women or men... they are both good in their own ways.
How the song is composed...
What the lyrics are...
Who the target audience is...
So much goes into it. Therefore, between men or women, there is no real winner.
Sometimes, a certain song is only meant for a certain singer because only he or she can hit the notes and give the right feeling.
Females appeal more to people because they give off a warm or sensual feeling at times. There could be cuteness or more vibrato as well, depending on the singing style.
Especially when it comes to eroge or anime, females attract more customers. Also, mostly females can hit the high notes for songs.
That doesn't mean there aren't men who are unable to hit high notes or aren't popular for eroge or anime.
Just comes down to the target audience and what most will like. Sales are important too I suppose.
Lots of great artists and music out there. Who you like is what matters. Gender is of no personal importance.