I’ll go outside the box and say Battle City in

Yu-Gi-Oh!

Mine is the Duelist kingdom in Yu-Gi-Oh

I'm a sucker for the dark tournament in Yu Yu Hakusho

Chunin Exam was amazing BUT MHA'S UA SPORTS FESTIVAL ARC IS THE BEST for me

Chunin Exams all the way

Most of the Chihayafuru tournaments...

^ yes Chihayafuru tournaments were pretty good

Still my favourite would be tournament of power and chunin exams would be second

Duelist kingdom is just so nostalgic