If I had to pick my top 5 from the NIGTC set it would be: 1. Beale on Revelation, 2. Ellingworth on Hebrews, 3. Thiselton on 1 Corinthians, 4. Nolland on Matthew and 5. O'Brien on Philippians (I don't care about the P. dilemma it's still very useful).
This list is pretty much why I bought it as well. And these individual volumes more than cover the cost of the entire set. Not to mention the value of those volumes not listed here.