Mostly, when I create a character I'm putting myself - or at least an idealised version of myself - into the game, so white human male it is. Sometimes, I try and recreate favoured characters; my next roll in Skyrim is probably going to be a rough likeness of Quick Ben from the Malazan series (my current being a female elf). But for the most part, I try to make a fantasy version of me. Boring perhaps, but I'm usually more focused on the rest of the game than my avatar.

 

I vary the gender based on such diverse criteria as what I feel like taking at the time and whether it will have an effect on the game. Appearance plays a part, I suppose, but it's not something I give particular thought to outside of choosing what the character will look like.

 

I've been a female on Skyrim for nearly all of my runthroughs, because there's a perk that gets opposite gender shopkeepers to give you more cash. And a lot of what I end up picking up and selling is arms and armour. Most weaponsmiths are male.

Unless there's an actual effect, I'll normally play as a male.

I rarely play as a human because they're often balanced - they default race. And I don't want a balanced character.

I want a mage who can kill everything with fire and lightning before they see me. I want a barbarian that can literally rip you in half. Using his eyebrows.

Or I want to be able to breathe underwater, and never worry about poison, or disease. Or I want to see in the dark without having to remember to carry torches everywhere.

 

In MMO's I'll generally play female character if the model are done right and if it fits with my vision of the class (WoW - NE Druid or Rogue). I like to think of a character concept and then choose which class, race, and gender will be the best to convey the feeling I'm aiming for (it will also depend on the setting of the game).

 

Maybe it says a lot about my self-esteem, but I would never want to play as myself in a game.

 

Picking a character is a pretty complicated process for me. In RPGs I will likely decide on a class first and then look at the available races for that class. I tend to choose unlikely or rare combinations. If everyone is picking an Undead Priest, I will pick Troll Priest, etc.
At the same time I avoid the silly/cute race(s). I can't really get into that.

In very story-based games, like most Bioware titles, I will stay closer to human than in other titles. (Elves and the like I consider to be almost the same.)

I'm not quite sure when it started, but I've also begun to choose female characters much more often than I used to. Might have started even with Jennifer Hale in Mass Effect.
But mostly it's probably a desire for different perspectives. I don't think I would be good at actually role-playing a female character, but experiencing a story from such a viewpoint is fun.

I also have no desire to recreate myself in a video game. That seems much more weird to me than playing an orcish witch or something like that.