If I'm going purely by playtime, then once again Animal Crossing would easily take the top spot at 550+ hours.
Unfortunately I can't see my longest played games so I'm guessing for some, but I know Pokemon Sword and Minecraft are sitting at over 200+ hours each as well.
Some of the games over 100+ include Breath of the Wild, Pokemon Let's Go Eevee, Final Fantasy X | X-2 HD, Skyrim Remastered, and Stardew Valley. There might be another one in there that I missed, but unless I start opening all my games and checking their times in my profile I'm not gonna remember. Hopefully Nintendo updates the Switch to make it a bit easier for us in the future.