Depends on what genre
Mario Odyssey and Breath of the Wild are amazing single player games, with Odyssey having a Player 2 option
If you're an RPG fan, Xenoblade 2 is a great pick
Splatoon 2 is a weird one.. a lot of people, myself included, really like it, but not all shooter fans do.
Overcooked 2 is a great party game, if you don't own it on other systems