The word "awareness" by its very nature should make one think of perception. Therefore "self-awareness" has to do with introverted perception. The four IxxJ types are the most self aware. I'd also assert though that feeling aids both interpersonal and intrapersonal skills, so I'd say IxFJ's are slightly more self-aware than IxTJ's (but only slightly). Likewise ExTP's are the least self aware type, but at the same time the most insightful in regard to their external environment.
In regard to INTJ's I'd say what makes them unique in this area is that they are incredibly self-aware while being very clueless about what makes other people tick. The INTJ makes complete sense to themself, but they might not understand their place in the world, because most other people don't make sense.