Any sport that crowns individuals like tennis, golf, swimming, track, or cc would be in the discussion, for the individual title.
Team sports can get a few talented athletes to take them far. It's hard to know if tennis is or isn't. For Florida and USC it hasn't been impossible. For other teams, it seems like it is lately.
My vote would go for:
Easiest = men's basketball
Toughest = men's golf individual