I'm
always an I, and almost always a J (but I love
nothing better than a deadline, I must add, and really I seem to identify much more with other P's).
I'm sometimes strongly
both S+N, depending on the questions.
I'm apparently too soft-hearted to be a pure T-type, but far too fact-oriented to be an F.
The S+N balance is the one that is close to 50-50, though it always seems to lean just slightly to the S.
Then again, most scientists I know have that S+N profile-- if we didn't, we would probably be engineers, KWIM?

Just kidding.
ISTJ or ISTP seems to be my "persona" to the world. It's how I seem professionally, anyway. I'm the one that will pull an all-nighter to make things right (even if I didn't create the problem to begin with).
With friends and family, however, I can come across as much more the INTP... and truly, I strive to be MORE that person. I don't always succeed, by any means.