This is a subject that first came about around a year ago or so for me.
I was trying to determine what would be the most objective type in the MBTI, and I felt confident in my accuracy when I decided that NTP would be more objective than any other three letters(to which I had some agreement from others that I know).
But I was then forced to determine if the ENTP or the INTP would be more objective, and I have been uncertain to this day.
The INTP could be assumed more subjective because of their rather self-contained means of thinking. We could argue that you'd need to pay more attention to the outer world to be objective, like an ENTP.
But look at it this way...
The ENTP gets much more caught up in the events around it. What I'm getting at here, is that you can sometimes be so deep in something that you lose sight of it. The INTP has the advantage of the "man from mars" effect. Social pressure and engineering should not have much affect on an INTP, where as they should on an ENTP.
In general, one might still be conceptually leaning toward the ENTP on this, but my question is also partly based on personal experience.
In my experience, the INTPs have been more objective than the ENTPs.
Is that just a fluke?
I guess the first function could make no difference at all, resulting in a tie.