As of this point, my top 5 are:
1. Football
2. Basketball
3. Boxing
4. Track and Field
5. Motorsport
In regards to "votes", the main 4 sports in America are NFL, NBA, MLB and NHL so it's a safe bet that those should be in the top 5 and rounding out the top 5, I would say it's either boxing or golf or motorsport...
I think the top 5 will still be the same in a decade.