My pick would be Mixed Martial Arts (MMA) as I have always been facinated with Bruce Lee, Jackie Chan, Jet Li, Samo Hung, Donnie Yen etc as a kid so when I first saw the UFC I was hooked! and since then I have been lucky enough to attend two live UFC events which were incredible!
There is something very real, raw and primal about two men or women getting in the octagon to see who is the best and giving it their all, almost Roman Gladiator in the Colosseum-esque I'd imagine! It is incredibly exciting to watch these incredible athletes step inside the cage to see who is the best. Also as it is a fight it really gets at you as it really is REAL... not like football (soccer) players who roll about the floor as if someone has launched a cannon ball at them when they haven't been touched, these guys and gals are the real deal.
Over the years I have seen some truly epic battles, the one that always sticks in my mind is Jon Jones VS Alexander Gustafsson.... OMG, that was a WAR... two guys, giving it there all, like seriously at some point they must have been like "im not gonna make it" but forwards and onwards they go, a real testament to human spirit and the skills these fighters posses. Speaking of the skills the more you understand the science behind MMA you realise there is SO many tactics at play and strategies and it is not just brutal cage fighting as uninformed people would lead you to believe.
Also it really is a universal sport, fighting is in every culture and nation as many have there own martial arts of fighting methods over history unlike some sports which can be huge but are very regional across the globe.
Just as a bonus I love how you can watch different body types and styles go at it and it may not have the outcome you expect as big muscly guys can look super intimidating but I have seen many times if the less muscled fighter can survive the early onslaught the big tank gasses out then it is a looooonnnnngg night for them!
Anyways I could leave a highlight video with tons of cool moves and KO's but heres some highlights from the one fight that always sticks in my mind I mentioned earlier! Enjoy!
https://www.youtube.com/watch?v=VWoblLV1bTo