As a football fan I don't find your concept that appealing, but I do see the logic. To answer your question the NFL has 10 times the viewership and almost twice the revenue as the NBA. The comports with my experience. The NBA is far more niche these days.
For 2023, the NFL generated $13 billion in revenue, while the NBA generated $10.8 billion in revenue. That's one heck of a niche.