oof
I'll always hold a special fondness for Naruto's chunin exams since that was like the first one I saw.
MAR's holds similar impact, since that was the first full manga series I collected around the same time and ended on a great tournament arc!
Loved Fairy Tail's Grand Magic Games arc.
And lately (late last year), I played this really great indie game "Battle Chef Brigade" that's effectively structured around a big Tournament.