From the film I've watched on JJ here are his top 3 attributes:
1. Court vision - never telegraphs passes; 3 steps ahead of what's happening on the court
2. Ball Handling - can weave through traffic with elite skill and uses body to position ball away from defenders
3. Body control - absorbs contact and finishes with precision around the rim
...but his most important attribute might be his personal character: persistent, mentally tough, and exudes a positive attitude which will make his teammates better.