For me it's Dota by miles, but that wasn't true until I'd made a huge investment into learning what in the world was happening on screen.
For things you can enjoy immediately without doing hours of homework, my votes go to Rocket League and StarCraft.
Congrats to
azuarc
, Mario Kart 64 AND GameFAQs Contest Legend!
board8.fandom.com/wiki/The_Show | thengamer.com/xstats