Human, and glad of it.
I'm not slender, graceful, and arrogant. I'm not squat, gruff, and clannish. I'm neither short and rotund nor slight and athletic. I'm not diminutive, curious, or particularly interested in crafts. I'm not mildly effete and outcast with a gift for making people not hit me because I'm outcast. I'm not hulking, brutish, and stupid.
If I had to choose a nonhuman race from the core rules, I'd say tiefling. I'm far too interested in the darker side of human nature and tempted by my own selfish, violent, hateful urges (relax; I'm very good at resisting temptation) to pick anything else. I'd make a pretty decent tiefling trying to come to terms with his heritage without going so far in the other direction as to be noble and self-sacrificing . . .
. . . because hey, I'm only human.