my son loves sports. we often find him watching a soccer game between 2 teams i've never heard of or a college football game between 2 tiny schools. i voted soccer, football and basketball for him watching, although he does watch some hockey and baseball as well, just not as religiously, and typically only for Philly. those other sports he'll watch anyone who's playing.
he owns at least 3 soccer jerseys. 1 is for the Union, the other 2 (or more) are for some of his favorite world players (messi, renaldo). he has 3 football jerseys currently. a mccoy eagles, a wilson seahawks and a gronk jersey. for gifts, he is always asking for jerseys of players he likes. he owns 1 basketball jersey and that's steph curry.
i was only going with "jersey" but he owns a dozen or so t-shirts for football, soccer, baseball, and hockey.