When I play, I choose, almost exclusively, humans. I think that, in all of my years of playing D&D, I have played 1 Dwarf, 1 Elf and 1 Half-elf. Everything else has been human.
As for why, I suppose it has to with my influences. Outside of Lord of the Rings, the fantasy stories and movies that influenced me feature protagonists that are exclusively human I suppose that this is why I don't care for the majority of DnD fantasy races as PCs and/or in concept. This dislike includes, but is not limited to: illumians, darfellan, shadar-kai, githyanki, githzerai, dragonborn, shardminds, dhampyr