What color do you play?

White. It tends to show up best on the board.

The only game with strict color selection is Carcassonne with the family.
My Mom gets red, her favorite color.
My Brother-in-Law gets blue, he is a police officer.
My eldest son gets gray, because blue was already taken.
My youngest son gets green, his favorite color.
I take black, because I have always taken black in Carcassonne.
Yellow is left for a sixth player, if we can get one.

I play yellow for four reasons:

1) A friend of mine hates it, specially when it's transparent
2) It's bright and easy to tell apart. I also like the shade it tends to come in in most games.
3) Yellow cards in Netrunner are like, good.
4) It's not a primary colour while not being as omnipresent as purple is in games.

Well, as noted by the inspiration for this thread:

I take red because that's generally how I approach games: aggressively. My all-time favorite 40K army was Dark Eldar, if that gives you any idea. But there's also Liverpool.
I also will take black, because that's a favorite color of mine and makes up a good chunk of my wardrobe. It goes great with my two cats, one of which is mostly white and the other is all white.
I'm also prone towards purple, especially in Euros, because it gives me the Roman Imperial purple thought.
But I'm also prone to trying to achieve color synchronicity. If I'm playing River in Spirit Island, I'll reach for blue. If I'm playing Earth, I'll reach for yellow. Those are the colors that seem to make sense with those spirits.

Lately, of course, I've found myself playing a lot of games where the color is predetermined (Blood Rage, Theseus), so I guess I haven't thought about this much in recent days.