If an RPG (or any other game) is open-ended in terms of selecting the gender of a main character, I'll go for a male one, seeing that I'm a guy myself. It's more to just reflecting what you are, if you ask me. By the way, why do you want to include some certain attributes on the different genders such as one has certain advantages/disadvantages over the other?
In my honest opinion, I much prefer playing a game that has a set main character (be it male or female) rather than one that you can customise to your heart's content. Why? It is because, you feel that the main character plays a very important role in the game and that character will be guaranteed a personality and a voice compared to a character that is customisable. Furthermore, that type of main character would be more in-tune with the surroundings and the interaction with NPCs.
However, if the main character is one that you can customise, I kind of feel that you are playing the role of a character that seems very detached from the events of the game. At times, I felt like you are directing the game rather than playing the main character. Furthermore, the character would surely be a mute and have no personality at all.