INTJ is my favorite outside of INFP. I've tried the INTP forum, but I don't quite understand Ti, and they've got Ti in overdrive there, lol. However, I find their sense of humor quite charming. ENTPs are hilarious, but I don't frequent them too either.
INTP is my favourite. I feel at home there.
But I also like a lot ENTP. I usually just read it, don't partecipate a lot, but I like ENTPs in general because they are always sassy, insolent, witty and sharp.
Sometimes they just make my day.
I like INTJ forum, lurking in there often. Most INTJs are quite matter of fact and not ornery. I like that; efficiently to the point.
It's rather amusing that often the opinions are what I would have said, too, even though I am the feeler cousin. I think the dominant Ni is really a strong influence on how INTJs and INFJs perceive the world.
ENTPs are like joksters, half of the time not serious.
ENTJs are....very blunt and unapologetic.
INTPs have the most opinionated and out there posters among NTs (and long winded, too).