I feel closest to ENTJ; they make perfect sense to me though their efficiency sometimes intimidates me. INFJ is a close second; my INFJ friends and I get the way each other's minds work, though we have completely different priorities.
INTP and ISTJ share a distant third place. I don't feel particularly close to either of them compared with types I share fewer than three letters with. I actually think I feel closer to ESTJ () and to all the other N types than I do to ISTJ and INTP - but I suppose that could be because I don't have any INTP or ISTJ friends whereas I have friends of the other types. Or is it the other way around?