You should start learning about and watching UFC. Muay Thai is a fun martial art to learn. So was Brazilian Jiu Jitsu, but I got tired of spraining my ankle and not being able to move my neck the next day.
I should have specified team sports, as in the four major American sports leagues.
MMA is always worth watching. When I was younger, I trained with one guy who still trains fighters. My daughter still goes to martial arts symposiums to train where a lot of the big names appear.
Have you ever heard of Bill "Superfoot" Wallace? He was the Pro Karate champion in the 70's, pre MMA. He was also John Belushi's bodyguard, LOL. My daughter goes out of her way to train with him. Hilarious guy and can still get his foot up there at his advanced age.
I might start paying attention to MMA with the same detail I was with NFL.