Mostly humans, sometimes half-elves, because those are the least restricted and the least pre-determined. And maybe the occasional token dwarf, gnome, or halfling. To me human characters are a blank sheet of paper, they can be whatever I imagine them to be. It's a lot harder to imagine the other races without thinking of all the fantasy clichés usually associated with them. And then there are the gameplay aspects, too. I hardly ever choose elves because they can't be resurrected in FRUA, and I hardly ever choose thieves because that seems rather pointless in FRUA, so I'm not surprised halflings are not among the most played races, even though I like them (I do occasionally create a halfling cleric, just to have some more variety). Last but not least, I have to admit, my character choices are also strongly influenced by the selection of the available character icons, and there are often more varied icons for humans than for the other races.