Which League requires more skill, and which requires more pure athleticism?
To expand on the question, consider the following hypothetical:
You are a coach and need to fill in some roster spots (can be any position). You can pick anyone in the world to join your team who has never played the sport at a competitive level. Say you have 2 months to coach the athletes though. Which league would be easier to find athletes that could fit in on the team and would hurt you the least? NBA or NFL?