It seems like the easiest way for me to honestly tell someone about who I am is to inform them of my personal history. At face value, I imagine this information is a dry means of sidestepping the essence of the question, but I'd rather leave it up to them to make their own inferences and conclusions about my character than to convince myself that the contrived description I give them is true. Descriptions of personal history also offer measurable proof of my past abilities and skillsets, which ventures into territory closer to who I am, since abilities are more or less the footprints someone will leave on the world.
I do think my answer would be formed by my knowledge of my enneagram/mbti type. I think I've actually done this a few times but I wasn't satisfied with my description or how I appeared to have made an impression on the person I was speaking with.