The second game I ever 100%ed was Arceus and I still can’t stand the thought of picking it up again, years later. The first game was Horizon Zero Dawn, which is still fun.
I had a ton of fun 100%ing Super Mario Odyssey. There's a big amount of post-game content and a good amount of variety in exploring the different levels. Some of the moons need a guide though since they can be reallt vague.
I felt differently, so many of those stars and collectibles are uninspired filler. Trying to 100% it led to me significantly disliking it. They could have cut so much and it’d be a much tighter experience.