Which type do you know least about from real life? Like you don't have any friends who has this type etc. Never had longer conversations with them etc. You can define "least" how you wish.
I thought it would be interesting to know. Could you please also tell your own type, if it's not in your signature.
Of course this is something that changes with age.
I think the type I know least today is ESTp. I know some people, and I've talked with them occasionally, but that's all. I don't know why.