Super Mario Odyssey
I mean, I still have all the bonus stuff left and a bunch of incompleted levels, but I finished the main story. The whole game is a complete delight and the very last level is very fun. I feel like Super Mario 64 started a more open world experience for Mario but this really takes the game's theme of travelling and exploration to the next level, with lots of fun hidden nooks and crannies and just making a fun world to explore.
That said, Luigi's Balloonland game seems to have... limited appeal.